Minuteman launch keys!?
Here's the first image that gave me some clues:
Found on the web, it's a picture of one of the keyswitches. On first glance, it looks like a crappy wafer lock, but not quite. Then I noticed the patent number! (3035433) It's an Eagle lock, one of the combo sidewinder/wafer ones!
And this just about made me fall over!:
A freaking missile key in a souvenir keychain that someone photographed at the National Park Service's Minuteman National Park site in South Dakota! If I ever go to SD, I know where I'm stopping, and what I'm buying! Sadly, I can't find any of these on ebay, or any mention of them at all, other than that picture.
Now, whether it's an actual missile key, or something made just as a souvenir by Eagle is unknown, but I at least know what the keys looked like that they used to start a global thermonuclear war. Glad it wasn't just a freaking Chicago wafer lock...
Edit: Looks like Squelchtone found the same info, minus the souvenir, and posted it on LP101