My first question is what have you been feeding it for a year? How great of a feeder is he?
Some of my snakes I can tell before I ever put the rat in that they are going to eat because of their behavior when I come in the room with the rats(scent). Many are 1/3 out of their hide in ambush position and will hit the next thing that drops near them, thats what I call good eaters. Others are not so quick to eat so I will give them a lot more time without disturbing them.
My point is good feeders you should know pretty quick if he is going to eat and picky feeders may need more time and patience. So knowing the snakes eating habits should dictate. After 30 minutes I would say they party is over unless the rat has found some great hiding spot and the snake is still actively searching.
Always make sure your rats are hydrated and not starving as they will chew each other up(let alone your snake) if they are dehydrated and starving. I feed almost 100 snakes live every week safely without problems.
Another rule I use is I only feed live rodents to snake that the snake can easily control with a strike. For example my boa eats prekilled because she gets fed really big rats that could possibly defend themselves. My ball pythons get fed much smaller rats in comparison so that they can just about kill or at least instantly control them, so not much resistance or fight at all. Thats why I like rats better because a smaller baby rat is not as scrappy or aggresive as an adult mouse. They have alot less fight yet have more weight.![]()