Place the chicken gizzards, celery, onion, bay leaves, and 1 teaspoon of celery salt into a saucepan, and pour in enough water to cover the gizzards by 1 inch. Bring the gizzards to a boil, reduce heat to low, cover, and simmer until tender, about 2 1/2 hours. Pour in more water during simmering, if needed, to keep gizzards covered. Remove the gizzards to a bowl, discard the celery and onion, and reserve the broth.
Season the gizzards with 1/2 teaspoon of celery salt, the seasoned salt, pepper, Italian seasoning, garlic powder, cumin, and hot sauce, stirring to combine well. Pour 1/3 cup of the reserved broth over the seasoned gizzards, and refrigerate for 30 minutes or more, stirring often. (Save or freeze the remaining broth for another use, if desired.)
Heat oil in a deep-fryer or large saucepan to 375 degrees F (190 degrees C).
Place the flour in a plastic bag, and pour in the gizzards with their seasoning. Shake the bag to thoroughly coat the gizzards with flour. Gently lower about 1/4 of the gizzards per batch into the hot oil, and fry until golden brown, about 5 minutes per batch. Drain the gizzards on paper towels, and serve hot