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

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_usergroup_privileges",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "usergroup_id"
      ],
      "key_length": "3",
      "rows": 2,
      "filtered": 100,
      "using_index": true,
      "attached_condition": "(`_testcscart`.`cscart_usergroup_privileges`.`usergroup_id` in (0,1))"
    }
  }
}