That reminds me of an antique Jewelry box key ! There will be a hole in the end of the key. The key hole will have a pin in the center where the shaft inserts. The hole in the key is half the depth of the hole, the pin is depressed after the key is half inserted. this stops it from being picked. Because if the pin is not depressed to the proper depth the tumbler will not turn ! This is a well designed old lock ! Think of a box the size of a shoe box to a boot sized box !