Use the key.

The one in your hand. Use it.

That key in your hand. The copper thing. Shinney like. Put it in the door.

The freaking key that I have given to you. The one that you're holding. Long, skinney, shiney like brass, with grooves and notches in it. Take it in your finger and thumb, put it to the keyhole and turn it.

The key does nothing for your in your hand, you have to apply it.

That door isn't much of an obstacle if you would just use the keys you've been given.