I've never understood why people doubt a snake's ability to eat.
Thousands of years of evolution have taught my snakes to kill live prey, and that is what they do.

As long as you don't leave a rat or mouse unsupervised for a long period of time, you're fine.

If give them their food and check in half an hour to see if they have eaten. If not, it's removed. 90% of the time they nail it in the first 30 seconds. I make sure the grip is good and the rat's not biting, and I leave them alone.