I thaw by leaving the rats out near my snakes. Wait a period of time based on the volume, usually however long I'm at work or sleeping, turn on a lamp so all the heads are around the bright spot (leaving the bright spot itself without any rats under it). Wait a few minutes for them to get warm (5-10), and offer them to the snakes.
Usually by the time the rats are thawed the snakes are in feeding mode
Same for my Savannah but I don't bother warming them and just put them near the basking spot