Some supermarkets in Bishkek and Osh are open 24 hours 7 days a week. They are available during the weekend as well. So if you need to buy some drinks or snacks you may easily find them. Alcoholic drinks are also in free sale.
In small towns they work till 9-10 pm. In small villages sometimes there is only one shop with limited choice of products.
If you want to buy fresh fruit, it is better to go to bazaar.