Whether captive or not snakes are literally perfect predatory killing machines. I'll grab a rat by the tail and as soon as they grab the scent (usually before I open the top of their feeding boxes (yes I feed in separate tubs) that things feet don't usually hit the ground before they got them wrapped up for the good night kiss.
Now my male is kind of picky and I'll watch him if the rat is getting curious and freaking him out that's a wrap, I pull the rat out and try again in 3-4 days. Typically I carry a knife or similar object if they get a bad strike (rare) to stick in the rats mouth while being constricted. (However they've been knicked before which people honestly over exaggerate snakes are INCREDIBLY resilient animals) now if you're leaving live in the enclosure too long I've seen instances where they'll chew a snake up I usually give my male about 10 minutes and my female requires no time, she's a power eater. however if you're watching them eat like I do and a rat gets a little aggressive you're right there to intervene.