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

Query time 0.00035

JSON explain

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