These types of keys are infamous in the Legend of Zelda series. In these games they are called small keys.
Keys of this type are implemented in many action-adventure games.
The what-could-be-called controversy associated with these keys is that one key will open any of the doors that can be unlocked by that type of key. However, after the key is used, it disappears and cannot be used to open any other doors with the same lock type.