Trash 'em! Might make your snake sick, in the UN-likely event he'd even take them. Sitting at room temperature, the germs grow even FASTER than in our
food, because you're talking about whole prey animals with a gut-load of bacteria waiting to proliferate. Freezing does NOT kill bacteria, it just slows down
the growth substantially, so when you re-thaw & warm these, they'll be really gross. When such prey is re-offered it's not unusual for the gut to split open
as the snake grabs it. Re-freezing after not only thawing but warming & laying around at room temps. is a no-go.
Properly-frozen & packaged* should keep in freezer for 6-12 months easily, *especially if vacuum-packed individually, that's the best way. Sniff test them
after thawing.