SELECT 
  privilege 
FROM 
  cscart_usergroup_privileges 
WHERE 
  usergroup_id IN (0, 1)

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "2.81"
    },
    "table": {
      "table_name": "cscart_usergroup_privileges",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "usergroup_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 2,
      "rows_produced_per_join": 2,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "2.41",
        "eval_cost": "0.40",
        "prefix_cost": "2.81",
        "data_read_per_join": "208"
      },
      "used_columns": [
        "usergroup_id",
        "privilege"
      ],
      "attached_condition": "(`webmarco`.`cscart_usergroup_privileges`.`usergroup_id` in (0,1))"
    }
  }
}