I had an escape a little while ago and there are a lot of things you can do. The first thing you should do is search near the escape site and work out from there, usually they don't go far. Check every place, even if you think it's too small. I would leave his cage open and possibly put it on the floor, sometimes they will go back home. Night is when they are active and your best bet is to leave the lights off and keep things as quite as possible. They tend to travel along the walls, so you and put plastic shopping bags there and you might be able to hear them if the snake happens to go by them. Leaving a heat mat with a hide near the escape site might lure him back. Depending on how big he is and what he likes to eat, you might be able to make a trap out of a plastic soda bottle and place a thawed rodent in it.

These are all the things I tried, and none of them worked for me because she was in a completely different room, but I did eventually find her. Sometimes you just need a little luck. They can stay hidden for long periods but usually eventually come out looking for water.

Good luck finding him.