Instead of paying a bank for a safety deposit box, we bought our own fireproof lock box that we can pick up in a hurry, if needed. Everything inside is obviously easy access.
A burglar can pick it up in a hurry too.
It is a real good idea to bolt it to the floor if you have not already. I saw a TV show once done by a former burglar who stated they always carried a hand truck for lifting up safes and carrying then out to their van/truck.