Bring a large pot of salted water to a boil. Add the spaghetti and cook according to package instructions until al dente. Drain and set aside.
In a medium bowl, toss the shrimp with olive oil, garlic powder, smoked paprika, salt, and black pepper until evenly coated.
Preheat the air fryer to 400°F (200°C) for 3 minutes.
Place the shrimp in a single layer in the air fryer basket. Cook for 6 to 8 minutes, shaking the basket halfway through, until the shrimp are pink and cooked through.
While the shrimp cooks, melt the butter in a large skillet over medium heat. Add the minced garlic and red pepper flakes and sauté for 1 to 2 minutes until fragrant.
Add the cooked spaghetti to the skillet and toss to coat in the garlic butter sauce.
Add the cooked shrimp to the pasta and drizzle with lemon juice. Toss gently to combine.
Remove from heat and stir in the grated Parmesan cheese and chopped parsley.
Divide the pasta among serving plates and garnish with additional Parmesan and parsley if desired. Serve immediately.