Drill it

Sometimes there is a way to get behind the door -> If so, just unscrew the nut holding the lock in.
Otherwise drill it out - I use a 1/4" drill bit - drill right into the middle of where the key goes.

Imagine the sense of pride and devious skills you would gain by learning out to pick it without damage. I've had to this once so far and the kit I received as a gift a few years back actually proved useful. And it's only $21.

https://www.amazon.com/A-SL-GBB-Lock-Sets-Included/dp/B07VXFLB53/ref=sr_1_4

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Drilling doesnt hurt the coin door at all. It's very very easy.

Nice sharp 1/2 inch drill bit right down the center of lock. Takes 15 seconds.

I would suggest a couple of options:

1) If you have access to the backbox and/or lifting the playfield, i would scrounge around looking for the key. I have found many...MANY keys this way.
2) You can sometimes use a screw driver or butter knife to open it. If it is possible, open and look for the key hanging inside the coin door or on the inside of the cab.
3) If you have other keys laying around, you can test them. Some operators and collectors use "common keys" which open up a ton of different games. It's worth a shot. You can also pick the lock if you have the tools or skills.
4) Drill it. 1/4 to 1/2 bit are typically used to drill straight down the center and gain access. Replacement locks with keys run about 4-5 bucks. Look for double bitted 7/8 barrel/cam lock with keys. Home depot, lowes, walmart, Amazon, and eBay are great places to find them.

Here is a good example:

ebay.com link: 7 8 PINBALL MACHINE ARCADE GAME LOCK DOUBLE BITTED LOCKS QUALITY HAPP COIN DOOR

Put a trash can under the coin door to catch the metal shavings and drill it...its easy and only takes a minute

This should be obvious but that drill bit will be hot enough to set fire to paper immediately after drilling the lock. Let it cool of a bit before you take it out.

Source: My dumb 12 year old self.

I generally avoid ever suggesting lock-picking kits to anybody. While, yeah, Amazon does sell them, state laws do vary.
Without a locksmith license there's a lot of places where it's a felony to have them on you.

I assume its not, but in the instance that you have a lock with a tubular cam (round key) you can sometimes pick it with the end of a bic pen.
You basically pop the end off the pen, jam it in there, wiggle it around and try to turn it.

Also, sometimes I try the random keys that I have from various other machines before drilling.
Every once in a while one works.

I'll add that if you're going to drill it, be sure you use a quality steel drill bit. Nothing worse than breaking a bit off in the lock and being really unable to open it then.

Sheer curiousity...did you find a key inside?

I pick them, amazing what you can do with a paperclip with a few bends in it and a 90 degree pick.

Patience and pressure.

Or have someone run a shop vac as you drill the lock. It's a real mess if those shavings get into carpet.