Heat oven to 400° F. Cook the rice according to the package directions. Meanwhile, in a shallow bowl, combine the paprika, cayenne, thyme, garlic powder, and 1/2 teaspoon of the salt. In a saucepan, over medium heat, melt 2 1/2 tablespoons of the butter and add the lemon juice. Heat a large ovenproof skillet over medium-high heat. Working with 1 salmon fillet at a time, dip the top and bottom first in the lemon butter, then in the spices. Cook the salmon until blackened, 2 minutes per side. Transfer to oven for 8 minutes. Stir the corn, parsley, and the remaining salt and butter into the rice. Transfer the salmon and rice to individual plates and serve with the lemon wedges.