The short answer is that you can wire the compressor straight to 12v power with a switch and fuse, and run the locker anytime. Power on = locked, power off unlocks it. The compressor has a built in pressure switch that runs the compressor until a specified (low) pressure, then switches it off unless the pressure drops. Power on also closes the locker depressure valve. When the power goes off, the depressure valve opens and the locker unlocks. This bypasses all the "safety" doodads.

Not responsible for advice not taken...