So is their any dispensaries close to the airport ? Have a 4 hour layover

Yeah, but you're going to spend $60 to $100 round trip on a Uber

Yes

It's about half an hour to the nearest recreational dispensaries AFAIK. I believe the closest would be House of Dankness and High West Cannabis. You'd be cutting it close. Check Leafly or WeedMaps. Keep in mind you can't smoke in the dispensary or in public. Vaping in public with a pen is typically tolerated while also illegal.