AFAIK, most snakes won’t eat something that’s already dead.
They need it live and kicking so they can work it down their throat and not have any broken bones or whatever.
Not necessarily so. Back when I owned the aforementioned burmese python I quickly got tired of keeping live rabbits in an apartment. A little research at the library (no internet back then) told me that snakes will eat dead animals.
The rabbits found a new home in the refridgerator freezer, lovingly wrapped in aluminum foil. The snake ate them just fine. She did not bother to constrict them first. Even a snake can tell the difference between live prey and carrion.
BTW. If you do have a pet snake, THAW the food thoroughly before you put it in the cage.