Angelina first of all i would see it as a risk to leave the key at work, it can be very dangerous.
Another risk is that all one need do is read the manufacturers name off the lock box and look on Amazon where it is quite likely one can buy the same box and it will come with the same keys. They have very simple locks. I bought a Taymac and can now control the heat/cool in the workout room we use for track practice.
The problem here would be that someone could steal your keys easily, even if they did not know what they were for.