A mystery key would absolutely survive a drawer clear-out in my imaginary house.

Old receipts, gone. Dead batteries, gone. Key to a lock nobody can identify? Keep that. Obviously the lock will reveal itself the day after the key gets thrown away.

I like this tiny, silly kind of hope. A spare button might still find its shirt. A cable might turn out to belong to something useful. They aren't precious objects, but getting rid of them asks for a decision that keeping them neatly avoids.

There is a limit to my defence of the junk drawer, though. Once a cable or a tall object wedges it shut, the collection has become a problem. I'd probably blame the cable while continuing to protect the key. I haven't claimed to be fair about this.