This was dropped from the final version of the game however, Frictional Games later used the Crypt for Amnesia's expansion pack Justine.
You can either get the bucket of water to flush the key out of the pipe, or you can use the cell bar part on the pipe to get the key.
You can also drag the bed to the cell bars, remove the weak part of the cell bar and jump-crouch through it to get out. After removing one, the latter will trigger script announcing that you should not waste time on it. There are two bars that are loose and weak, one located at the upper part of the cell, where you can jump-crouch out of, and below on the bottom right-hand corner.
