I’ve been playing for a while and I can’t find a single use for key locks. Losing keys is very easy and if you lose it you’re locked out of your own base. I just keep the door open until I get a password lock.
So what’s the use for them? For any door higher tier than wood they seem counter productive only. At least if you lose a key with a wooden door you can bash it open.
The only time I use them is when making fake bases, hoping people waste their time breaking in.