idselect_typetabletypepossible_keyskeykey_lenrefrowsExtra
1SIMPLEuserrefPRIMARY,user_type_iduser_type_id4const1Using index
1SIMPLEuser_themerefidx-user_theme-user_ididx-user_theme-user_id4sportshu_test.user.id1Using where