3 minutes! Well in order to even produce a list I am gonna break that rule (hopefully not by more than 30 seconds or so)
Off the top of my head...
The La's - There She Goes ... This is definitely under 3 mins, an absolute classic.
Guided by Voices - Hold on Hope ... Utterly wonderful tune...
Shazam - Super Tuesday - In fact I am gonna put this album on as I write 🙂
The Bees - Chicken Payback - crazy crazy wonderful tune
Pavement - Spit on a stranger - Beautiful opening riff, and stupendous, fragile vocals.
Neutral Milk Hotel - In The Aeroplane Over The Sea - A stupendous album, and this is the fantastic title song
The Beatles - Here comes the sun - What can I say...I remember I used to own an old japanese MX5 import, and it was a hot day, driving along open top, and this came on... Oh the smile.
R.E.M. - The one I love - Stupidly simple, but stupidly addictive.
Belle and Sebastian - Get me away from here, I'm dying - Great tune, makes me want to move...
Delays - Nearer than Heaven - sounds like a girl, but a killer track.
Men at work - Overkill - (A wonderful song. Colin Hays solo acoustic version may even be the definitive...)
Thats top of my head, breaking the 3 minute rule in most cases, and blurring the definition 'pop' somewhat maybe.