Upvote:1
Assuming your flight into Muscat is on schedule, you should be okay. The airport recommends that you allow a minimum of 60 minutes. As both your flights are with Oman Air, they should sort another transfer for you if your plane is delayed.
http://www.layoverguide.com/2014/02/layover-in-muscat-oman.html
If you request it at the check on desk in London, they should just transfer your luggage to the final destination when you change planes. This can vary by airline though.