Place a rack in the center of your oven and preheat the oven to 400 degrees. Place the shrimp in a large mixing bowl, drizzle with olive oil, then sprinkle with chili powder, cumin, smoked paprika, and kosher salt. Toss to coat, then spread the shrimp on in a single layer on a large baking sheet. Roast for 4 to 6 minutes, just until the shrimp are opaque and cooked through (do not over cook, or the shrimp will be chewy). Set aside.