Hola Mr. Pax -
xxx
General aviation airplanes generally have keys.
When I owned an airplane, a Super Cub ex Army, there was no key.
Anybody could steal it.
xxx
No "ignition key" with airliners.
I have a key ingraved "BOEING" (with a part number on the other side).
That is a cockpit door key. Worked on all Boeing airplane cockpit doors
Nowadays, with "reinforced" cockpit doors... that key is a little ridiculous.
xxx
Moonlighting occasionally, flying a Learjet.
They have a key, operating an electric motor on the fuselage door steps.
xxx
Question - are you planning to steal a 737 and fly it away...?
I have a book "How to fly Boeings in 10 lessons" for sale, good condition.
Or would you prefer the edition "Flying for dummies...?"
xxx
Happy contrails