The safest place on earth, for things you want to not lose, is a myth. Might as well just toss them anywhere. It gets worse with a second person keeping track of things and then compounded by age. I feel for your loss. I have picked several locks when the key disappears, but people get nervous when they watch you picking a lock. Replace the lock and you will find your keys within a week. Do not ask how I know. Then my lovely wife, remembered moving them for me to an safer place.