I have seen locking devices for valves, circuit breakers and, of course, some disconnect switches have locking handles. I have never seen such a device for a push button.
Why not? A push button is not a Lock-Out Tag-Out (LOTO) device. It is a control device and does not serve to remove or isolate a source of energy. An electrical oopsie during troubleshooting can simulate pushing the button.
The lock used for LOTO is MY lock. I own it, I have the only keys and there is no master key. If I screw up and leave something locked out when it shouldn't be, call me back in at my expense to remove the lock. Cutting a lock should be a fireable offense. My life, my lock! Oh, and I need to put a tag on the lock explaining why the circuit is locked out. It must have my name on it so the management knows who to call.
Everybody has reasons why things can't be turned off. Well, call me back when they can!