There is a shop girls sell food. they are uncovered/not wearing Hijab so is it permissible for boys to buy food even there are so many shop where boys sell food?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

There is no doubt regarding the permissibility of the act of buying from a shop where unveiled girls sell food, but the issue that has to be considered is the issue of looking at those women. Some scholars are of the view that it is permissible to look at women's faces when necessary, such as when selling and buying if one is secure from temptation.

The Kuwaiti Fiqh Encyclopedia reads: "The Maaliki, Shaafi‘i and Hanbali Schools stated that it is permissible to look at the face of a non-Mahram woman upon attestation, and when buying and selling; and she is also permitted to look (at the man interacting with her). Imaam Ahmad said: A man does not give his testimony about a woman unless he knows her as a certain individual, and if he interacts with a woman in sale or hiring contract, then it is permissible for him to look at her face so that he would know her as a certain individual.

However, it was reported from Ahmad that this is disliked if it is a young woman and not an old one; he may have disliked it for someone who fears temptation, or someone may do without resorting to interacting with her. However, if there is a need and there is no temptation, then this is acceptable." [End of quote]

But if these girls who work in the shop uncover what exceeds their faces, like their hair and other parts of their body, and a person needs to interact with them, then he should fear Allaah as much as he is able and lower his gaze from looking at whatever parts of their bodies that are not permissible for him to look at.

Allaah Knows best.