What can I do there with a 4 hour layover? Could I go anywhere during these times?

Not really, flushing meadow park, is near. But 4 hrs is not a long time with NY traffic. If u r in terminal B. There is a decent food court, very new terminal. The others are in he midst of construction

Pretty dicey given the traffic and construction at LGA. Maybe a quick tour of the Queen's Museum which is at the old 64 World Fair site. But I'd find a lounge and hang out at the airport with only 4 hours.