Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1200084

MacLeod's description:

Time: 3:44 - 124 BPM (Allegro - Pretty Fast) Genre: Contemporary
Synths, Percussion, Organ, Guitar

Okay, not quite a synth, not quite and organ - that thing is a mellotron. And it is cool. Interesting baroque changes in the B section. General Space-age cocktail party awesomeness for the entire piece.
ISRC: USUAN1200084 Bouncy, Humorous 2012