Buy a double cylinder deadbolt, which uses a key on both sides of the
door, and mount the lock at the normal height.

Fire hazard. Make sure you keep a key nearby, like behind a picture or
a floor mat or something.

Well, most folks keep the key in the lock most of the time. You take the
key out when you leave the house empty (keep it within sight of the door)
but at night you leave it in place.

Some folks put those locks in because they have someone in the house who
"wanders." (A senile old person or a kid with mental problems.) They
have to balance the fire hazard with someone "escaping" the house and
playing in traffic.