They can handle 100ºF (VPI 'ball pythons ref.) for short periods as long as they don't have a meal in the belly. The first issue isn't burns but they simply cannot digest food if it is too hot. Burns happen after the digestive system shuts down. My hands after I have been working hard often reads 101-2 Rats body temps are 99-101 it is unlikely that the normal body temp of a prey item is going to burn the predator.
100º won't burn a snake but it will stop eating and digesting food items.