SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description, 
  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 (
    8338, 8339, 8724, 8346, 8341, 8462, 8334, 
    8335, 8355, 8725, 8342, 8340, 8360, 
    8064, 8473, 8332, 8267, 8318, 8336, 
    7056, 8337, 8243, 8257, 8381, 8315, 
    8265, 8313
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00071

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "18.91"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 27,
      "rows_produced_per_join": 27,
      "filtered": "100.00",
      "index_condition": "((`primapearl_r_new`.`cscart_product_descriptions`.`product_id` in (8338,8339,8724,8346,8341,8462,8334,8335,8355,8725,8342,8340,8360,8064,8473,8332,8267,8318,8336,7056,8337,8243,8257,8381,8315,8265,8313)) and (`primapearl_r_new`.`cscart_product_descriptions`.`lang_code` = 'ru'))",
      "cost_info": {
        "read_cost": "16.21",
        "eval_cost": "2.70",
        "prefix_cost": "18.91",
        "data_read_per_join": "102K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "meta_keywords",
        "meta_description",
        "search_words",
        "promo_text"
      ]
    }
  }
}