One of the many surprising aspects of living in Central America and Mexico is the discovery that meat and eggs are usually sold unrefrigerated. The meat you buy this morning most likely comes from a cow that was killed earlier this morning and just butchered. Of course when business is slow, perhaps it has been a day or two since the animal was butchered. Your sense of smell becomes an important ally. When I am looking for a good butcher shop my nose and eyes are my best tools. When a shop looks clean, but smells bad, I keep walking.
There are many very clean and relatively hygienic butcher shops where meat can be purchased that use little or no refrigeration. If the shop or stand looks clean and smells clean the odds are quite good you will be able to buy some good fresh meat. If your nose says no, keep looking.