For aioli, whisk 1/4 cup mayonnaise, Sriracha, and 1 teaspoon lemon juice together in a small bowl. Set aside.
For crab cakes, add egg, 2 tablespoons mayonnaise, Old Bay, 1 teaspoon lemon juice, drained crab, and Panko bread crumbs to a large bowl. Mix until evenly combined.
Take 2 tablespoons crab mixture and form into a small patty. Repeat with remaining crab mixture.
Heat olive oil in a large skillet over medium-high heat. Cook patties for 5 minutes. Using a spatula, flip patties and cook until golden, about 5 minutes more.
Transfer to a serving platter and serve with reserved Sriracha aioli.