SELECT 
  p.tracking, 
  p.amount, 
  p.min_qty, 
  p.max_qty, 
  p.qty_step, 
  p.list_qty_count, 
  p.out_of_stock_actions, 
  p.product_type, 
  pd.product 
FROM 
  cscart_products AS p 
  LEFT JOIN cscart_product_descriptions AS pd ON pd.product_id = p.product_id 
  AND lang_code = 'ja' 
WHERE 
  p.product_id = 277

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "const_condition": "1",
    "table": {
      "table_name": "p",
      "access_type": "const",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "ref": ["const"],
      "rows": 1,
      "filtered": 100
    },
    "table": {
      "table_name": "pd",
      "access_type": "const",
      "possible_keys": ["PRIMARY", "product_id"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "ref": ["const", "const"],
      "rows": 1,
      "filtered": 100
    }
  }
}