Maya Sport is a diversified sporting goods store. It carries name branded products across many sports. You can find good quality hiking gear here.
The store is located about 10-minute walk from the old town. It is on the flatter area in the same shopping plaza as the Carrefour supermarket. As you are looking at the Carrefour, Maya Sports is in a separate building off to the side, right side IIRC.
Hope this helps.