It's kind of pointless to argue over what is the least painful way to kill a rodent for snake consumption. I know it's all in the best interest of the rodent to not be cruel, but I don't see how it's more cruel to whack a snake in the head or suffocate it than it is to let a snake kill it live. You end up with the same result whether it dies 2 seconds or 2 minutes after you inflict your intentions of death upon it. No matter what, it will die. I know the point is to kill it quickly, but it would probably suffer more in the jaws of a hungry snake than it will if it's being suffocated by a human.
With that being said, why does no one mention a mouse trap? No one can deny that those are quick and definitely work. Just grab the rodent with the tongs, hold it under the trap and trigger it to snap it's neck. Quick and easy.