45 degrees at night will do your snake some damage especially if it has undigested food in it's belly. The only time where 45 wouldn't hurt is when they hibernate. Assuming there is no food in the belly.When we "hobbyist" cool our snakes we make sure they have not eaten for at least 10 days or so. I wait two full weeks after the last meal ,and that the snake has defecated it's last meal before introducing it to the hibernaculum.
Barry