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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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    1451, 1183, 18, 17, 19, 1814, 1813, 1874, 
    1875, 974, 1574, 1575, 1812, 1811, 1507, 
    1853, 1856, 1918, 1919, 1862, 1861, 
    1857, 1883, 1860
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00109

JSON explain

{
  "query_block": {
    "select_id": 1,
    "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": 24,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (1451,1183,18,17,19,1814,1813,1874,1875,974,1574,1575,1812,1811,1507,1853,1856,1918,1919,1862,1861,1857,1883,1860) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id	short_description	full_description	meta_keywords	meta_description	search_words	promo_text	unit_name
17
18
19
974
1183
1451
1507
1574
1575
1811
1812
1813
1814
1853
1856
1857
1860
1861
1862
1874
1875
1883
1918
1919