Convert unix timestamp

Hi!

I got a bunch of video files I would like to rename.

location1_1564934192_4653268742467874325.mp4

The first part is a name that changes and then between the _ the unix time stamp and the last part is a hash I think.

I would like to rename them to YYMMDD??.mp4 where ?? is 01 andthen 02 and so on if there are more than one with the same date.

I guess this can be done with a script?
And that's out of my domains, I'm glad I've managed to figure out some basic regex ;)

Anyone able to help?