Use a few sheets of paper towel to pat the shrimp dry. Sprinkle them all over with the paprika, cumin, garlic powder, onion powder, and salt and pepper to taste. Mix until all the shrimp are coated.
Melt the butter in a skillet over medium-high heat. Add the shrimp. Cook, stirring, until the shrimp are pink and just cooked through, 2 to 3 minutes.
Squeeze the lemon half over the shrimp and sprinkle with parsley. Serve immediately.