According to the lookup on the mat site (mta.info, use Laguardia as the street address, Flushing, NY as the city and state)
HUDSON NEWS
LA GUARDIA AIR PORT
MAIN TERMINAL, QUEEN NY
11371
and
HUDSON NEWS
LA GUARDIA AIR PORT
U. S. AIR TERMINAL, QUEEN NY
11371
Sell the $10 and $20 cards, and
PARADIES LAGUARDIA INC
LAGUARDIA AIR PORT
DELTA FLGHT CTR, QUEEN NY
11371
Sells the $5 airtrain and $10 card, though not sure why they would sell the airtrain card, but it's the MTA.