There’s no need to boil or cook shrimp prior to frying it in the skillet for fried rice - in fact, this is likely to result in rubbery, overcooked shrimp with not much flavor. The high temperature for frying ensures that the short cooking time for the shrimp is sufficient to cook them through. If using precooked shrimp, simply add them to the rice later in the cooking process to ensure they are fully heated through to a safe temperature, without overcooking.