This key, complete with mesh, sprite and lock can be found in the WAD for Natla's Mines in the original Tomb Raider. It is found nowhere in the level itself though.
Using unofficial level editors, the key can be placed into the level. If Lara picks it up the name in the inventory is non-existent as no string for it exists in the game. If the previous is repeated for Natla's Mines in the September 4th build however, the key uses a placeholder name: "Level10A Key1".
