Welcome to TF. I think he meant a replacement lock, rather than just the key, Comodave..?
Those type of locks are always a bit dodgy anyway. I replaced mine on the main saloon door with a round style padlock and hasp, and for the pilot door, just a hook and eye on the inside which we could just unlock from the inside, as being a second door and not the main door, being able to lock it from the outside with a key was not necessary. That might not suit this poster however.