Pet stores can have extremely neglected and unestablished snakes. I would stay far away from that petstore and contact a breeder directly who can give you
1) a healthy, established and feeding animal.
2) correct husbandry information because the pet store obviously doesnt have a clue.(Not your fault, most petstores dont know and just offer very basic, outdated and/or generic even poor advice)
My first snake came from a pet store as well loaded with parasites and illness. Never purchased another snake from a store again.