Umm how do I use this key?

[The Ghost Pyro From Outerspace!!]

In the iron mine, go the rusty iron key. How the hell do I use it? I tryed just clicking the door, nothing. Tried to put the key in the hotslot, can't do it. Tried equipping the key, no where to equip. Tried applying the key to the door, it just gets dropped. How the hell do I use this damn thing? Why does using a key have to be so complicated?

[Kovi]

Actually, using keys is simple - if you have the right key for the door in your inventory, it will be used automatically when clicking on the door and the door will open for you. If you don't have the right key... you know the rest. Regarding keys in the Iron Mines, please see this post for clarification.