Pick through crab meat and make sure there are no shells. Place into a medium-sized mixing bowl.
Stir in bread crumbs, mayo, egg, mustard, lemon juice, worcestershire sauce, old bay, garlic powder, and salt. Stir until ingredients are evenly distributed.
Take about 1/4 cup of the crab mixture and shape into a patty. Repeat with remaining crab mixture. Spread flour out onto a plate. Dip crab cake into flour on both sides to coat and gently brush off excess.
Pour enough oil into a large skillet to cover the bottom and heat over medium high heat. Working in batches as needed, fry crab cakes in hot oil until golden brown 3 to 5 minutes on each side, adding more oil between batches.
Transfer fried crab cakes to a paper towel lined plate to drain before serving hot. Garnish with green onions.