Mix chicken stock, salt, sugar, thyme, and cayenne pepper together in a bowl to make marinade.
Place chicken thighs in a resealable plastic bag. Pour marinade over chicken. Squeeze out most of the air and seal. Place plastic bag on a plate. Refrigerate 4 hours or overnight.
Place flour on a plate. Beat eggs in a bowl. Place chopped nuts on a separate plate.
Remove chicken thighs from the bag; discard marinade. Dredge thighs in flour, coating all sides. Transfer to bowl with eggs and coat on all sides with eggs. Roll thighs in chopped nuts.
Heat olive oil in a skillet over medium heat. Fry thighs until golden brown and no longer pink in the center, about 10 minutes per side. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).