How do Cessationists interpret Matthew 7:21-23?

Most Cessationists that I know of of have a more nuanced understanding. They believe Jesus is speaking generally about unbelievers who think they have performed miracles but also may include an unbeliever who was in a ministry that actually may have performed real ones, such as Judas.

For the fake miracles - these are to be expected and I suppose even many today will find out they have no faith that claim such things:

9 The coming of the lawless one will be in accordance with how Satan works. He will use all sorts of displays of power through signs and wonders that serve the lie, 10 and all the ways that wickedness deceives those who are perishing. They perish because they refused to love the truth and so be saved. 11 For this reason God sends them a powerful delusion so that they will believe the lie 12 and so that all will be condemned who have not believed the truth but have delighted in wickedness. {The New International Version. (2011). (2 Th 2:9–12). Grand Rapids, MI: Zondervan.)

For the rare cases when unbelievers perform real miracles that are also included in this threat. John Owen presents some good examples besides Judas who might have been involved in casting out demons with the other Apostles.

But here a doubt of no small difficulty nor of less importance presents itself unto us,—namely, whether the Holy Ghost did ever grant the holy inspirations, and the gift of prophecy thereby, unto men wicked and unsanctified; for the apostle Peter tells us that “holy men spake of old as they were moved by the Holy Ghost,” 2 Pet 1:21, which seems to intimate that all those who were inspired and moved by him, as to this gift of prophecy, were holy men of God. And yet, on the other hand, we shall find that true prophecies have been given out by men seeming utterly void of all sanctifying grace. And, to increase the difficulty, it is certain that great predictions, and those with respect unto Christ himself, have been given and made by men guided and acted for the most part by the devil. So was it with Balaam, who was a sorcerer that gave himself to diabolical enchantments and divinations; and, as such an one, was destroyed by God’s appointment. Yea, at or about the same time wherein he uttered a most glorious prophecy concerning the Messiah, the Star of Jacob, being left unto his own spirit and inclination, he gave cursed advice and counsel for the drawing of the people of God into destructive and judgment-procuring sins, Num. 31:16. And in the whole of his enterprise he thought to have satisfied his covetousness with a reward for cursing them by his enchantments. And yet this man not only professeth of himself that he “heard the words of God,” and “saw the vision of the Almighty,” Num. 24:4, but did actually foretell and prophesy glorious things concerning Christ and his kingdom. Shall we, then, think that the Holy Spirit of God will immix his own holy inspirations with the wicked suggestions of the devil in a soothsayer? or shall we suppose that the devil was the author of those predictions, whereas God reproacheth false gods, and their prophets acted by them, that they could not declare the things that should happen, nor show the things that were to come afterward? Isa. 41:22, 23. So, also, it is said of Saul that “the Spirit of the LORD departed from him, and an evil spirit terrified him,” 1 Sam. 16:14; and yet, afterward, that the “Spirit of God came upon him, and he prophesied,” chap. 19:23. The old prophet at Bethel who lied unto the prophet that came from Judah, and that in the name of the Lord, seducing him unto sin and destruction, and probably defiled with the idolatry and false worship of Jeroboam, was yet esteemed a prophet, and did fore tell what came to pass, 1 Kings 13:11–29.

Owen, J. (n.d.). The works of John Owen. (W. H. Goold, Ed.) (Vol. 3, pp. 139–140). Edinburgh: T&T Clark.

Regarding how this verse applies to day it would mostly apply in the same way because Cessationsists may believe in demons and having them being cast out. With respect to the 'miracles' - these would be basically confided to those 'lying wonders' to be expected near the end. Not to say God is not able perform miracles. Even extra ordinary miracles. If God were to perform some extraordinary miracle like parting the Read Sea, through an individual, it would contradict our expectations, yes. However if it was in a manner that glorified his word it would also probably be supported by true Christians at large whether Cessationsists or not. Unfortunately the fake miracles and fake prophets seem more predicted in the future than the true. Possibly because once the scriptures were completed our faith is enabled enough not to rest on mind-boggling supported and because the Devil is enraged at the victory Christ has achieved in saving the elect, who can't be deceived.

12 The sixth angel poured out his bowl on the great river Euphrates, and its water was dried up to prepare the way for the kings from the East. 13 Then I saw three impure spirits that looked like frogs; they came out of the mouth of the dragon, out of the mouth of the beast and out of the mouth of the false prophet. 14 They are demonic spirits that perform signs, and they go out to the kings of the whole world, to gather them for the battle on the great day of God Almighty.

The New International Version. (2011). (Re 16:12–14). Grand Rapids, MI: Zondervan.

One of the problems about categorizing everything is that God can still do whatever he wants regardless of what disrespect it has to our categories. He need not give gifts and he may give them. For one hundred years he may give less of the Spirit to a wicked generation and than for one hundred years he may choose to revive them. We can't place unbreakable rules on him, however his rules upon us our sure. Jesus is reminding who is the Lord regardless of what we or others claim.

The example of Judas, the fake Apostle who was not born again, is similar so perfectly described below:

4 It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, 5 who have tasted the goodness of the word of God and the powers of the coming age 6 and who have fallen away, to be brought back to repentance. To their loss they are crucifying the Son of God all over again and subjecting him to public disgrace.

The New International Version. (2011). (Heb 6:4–6). Grand Rapids, MI: Zondervan.