A small rat is 50-80 grams. If anyone is paying small prices for 125g rats, let me know who you're buying from haha.

An XL retired breeder mouse would be close to 50g. Or a pregnant female maybe. A small rat could be about that size if you find a smaller small rat. So yes, it'd be OK to feed one to that snake as long as you get the right size. If you're worried about the rat being too feisty for the snake cuz of its size, you just pre kill it. Hold a pencil, ruler or butter knife behind its head and push down. Yank hard of the base of the tail. Boom, simply pre killed.