Encrypting an encryption key

from here and here (image source)

Whether you lock or encrypt a key, you'll need a key to unlock or decrypt it, so how do you protect that secondary key? You either get into an infinite loop of keys and locks/encryption or you accept that a less secure key unlocks the thing you're ultimately trying to protect.

In the case above, however, you could just break the glass, which is exactly the kind of backdoor authorities would love to see in encryption, but which would make us all less secure, just as this key is less secure because of the glass.