SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    18491, 18511, 18522, 18492, 18512, 18481, 
    18523, 18493, 18513, 18483, 18496, 
    18514, 18484, 18501, 18515, 18485, 
    18505, 18516, 18486, 18506, 18517, 
    18487, 18507, 18518, 18488, 18508, 
    18519, 18489, 18509, 18520, 18490, 
    18510, 18521
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00058

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "lang_code"],
          "rows": 33,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (18491,18511,18522,18492,18512,18481,18523,18493,18513,18483,18496,18514,18484,18501,18515,18485,18505,18516,18486,18506,18517,18487,18507,18518,18488,18508,18519,18489,18509,18520,18490,18510,18521) and cscart_product_descriptions.lang_code = 'ru'"
        }
      }
    ]
  }
}