We use a ziploc, empty butter container, and warmer water. Takes about 45-1hr to thaw. Usually 1 water change. You want them to where you can squeeze the rat and its guts feel slightly warm.

Some people re-freeze if the snake refuses. We do not. Bacteria starts as soon as the rat hits the water to thaw. We also always feed in a seperate tub to prevent tank agression. Some folks do, some dont.