LotGD Player Forums (Unofficial)

This would require a player to accept a key from the giver, rather than it automatically being given.

Another option that was suggested was that keys could only be given by those on a player's friend list

These two could also be combined, so that acceptance would be required if the players are not "friends", but those on your friend list did not require that.

As far as I know, there is not already a module for this, so it would need to be created.