SELECT 
  f.*, 
  d.description 
FROM 
  cscart_form_options as f 
  LEFT JOIN cscart_form_descriptions as d ON d.object_id = f.element_id 
  AND d.lang_code = 'ru' 
WHERE 
  f.page_id = 30 
  AND f.status = 'A' 
ORDER BY 
  f.position

Query time 0.00666

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "read_sorted_file": {
          "filesort": {
            "sort_key": "f.position",
            "table": {
              "table_name": "f",
              "access_type": "ALL",
              "possible_keys": ["page_id"],
              "rows": 9,
              "filtered": 100,
              "attached_condition": "f.page_id = 30 and f.`status` = 'A'"
            }
          }
        }
      },
      {
        "table": {
          "table_name": "d",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["object_id", "lang_code"],
          "ref": ["cscart.f.element_id", "const"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond(d.lang_code = 'ru')"
        }
      }
    ]
  }
}