It sounds both sill and obvious but don't lose the key. Long ago, after updating the standard locks on a belt to a high security Medico lock, my keyholder misplaced the key. It took some sort of frantic searching for about four hours to find. There was a backup key but it was not easily accessible. There was no immediate need to remove the belt so it was not an issue. It bothered the keyholder a lot more than it bothered me. The belt could have been removed mechanically, if necessary. The places she had been were limited between the time they had the key and the time they discovered it was missing. It was just a matter of careful and exhaustive search. But the keyholder felt they had damaged my trust despite my assurances otherwise.
Don't lose the key!
