Hi guys

I'm almost at the end of the game, but one thing still bothers me - there is one locked door just above the entrance to the bad wizard's tomb (Antediluvian Vault entrance) in the Champion academy. The door is near to the first jumping platforms on the way to the Moss rat sphere - just after you cross the broken floor,after the wooden "bridge" made from several wooden boards. So is there a key or button for that door

?