In a large bowl, combine the olive oil, smoked paprika, ground cumin, garlic powder, onion powder, chili powder, salt, black pepper, and cayenne pepper. Add the chicken thighs and toss to coat evenly. Let marinate for at least 30 minutes, or up to 2 hours in the refrigerator for more flavor.

Heat a large skillet over medium-high heat. Add the marinated chicken thighs and cook for about 6-7 minutes on each side, or until they are cooked through and have a nice golden-brown color. Remove the chicken from the skillet and let it rest for a few minutes before slicing.

In the same skillet, add the butter and sliced zucchini. Sauté for about 5-6 minutes, or until the zucchini is tender but still crisp. Stir in the fresh lemon juice and season with salt and pepper to taste.

Serve the sliced chicken thighs on a plate alongside the sautéed zucchini. Garnish with chopped cilantro.