Pat the shrimp dry with paper towels.
In a large bowl, whisk together the melted butter, lemon juice, smoked paprika, garlic powder, salt, pepper, and crushed red pepper flakes.
Add the shrimp to the bowl and stir to coat. Marinate the shrimp for 10 minutes. (Do not let the shrimp marinate for more than 30 minutes.)
Meanwhile, preheat the oven to 400 degrees F (204 degrees F).
Arrange the shrimp in a single layer in a large baking dish. Scrape any marinade left over in the bowl over the shrimp. (It will have solidified by this point, which is fine.)
Bake shrimp in the oven for 8-10 minutes, until opaque.