modern aircraft doors open inwards first, this is a really important design feature.

so therefore locking becomes irrelevant. even if some crazy person goes up to the doors mid flight and tries to disarm, unlock, and open them, they simply won’t open when you’re at altitude, even though the aircraft is pressurized.

long story short the difference between closed and “locked” is actually almost irrelevant in modern airliners when the aircraft is at altitude.