Suppose it depends how you want to define a safe, but if hobnails count then the Roman arca ferrata are much older again. Not that many have survived but there are a few examples plus buildings left with the base remnants of the concrete platform with a central iron anchor bolt.

While the Romans were undoubtedly superb engineers they didn't necessarily invent everything they were given credit for, and the arca ferrata safes might have been copied or adapted from earlier Mesopotamian, Syrian, Indian(etc) ideas.