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.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    21919, 21920, 21921, 21922, 21923, 21924, 
    21925, 21926, 21927, 21928, 21929, 
    21930, 21931, 21932, 21933, 21934
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00942

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id", "idx_product_lang"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (21919,21920,21921,21922,21923,21924,21925,21926,21927,21928,21929,21930,21931,21932,21933,21934) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
21919 Bracket - engine support, right<p>Part number 21825T6250</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21920 Bracket assembly - engine mounting left<p>Part number 21850T6200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21921 Cylinder head cover assembly, LH<p>Part number 224103N110</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21922 Cylinder head cover assembly, RH<p>Part number 224203N111</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21923 Adapter Assy-Oil Filter<p>Part number 224303N110</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21924 Bracket-wiring mounting<p>Part number 91931T6080</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21925 Bearing Pair Set - Crankshaft<p>Part number 210203N501</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21926 Bearing Pair Set - Crankshaft<p>Part number 210203N511</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21927 Bearing Pair Set - Crankshaft<p>Part number 210203N521</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21928 Bearing Pair Set - Crankshaft<p>Part number 210203N531</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21929 Bearing Pair Set - Crankshaft<p>Part number 210203N541</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21930 Bearing Pair Set - Crankshaft<p>Part number 210203N551</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21931 Bearing pair set - connecting rod<p>Part number 230603N501</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21932 Bearing pair set - connecting rod<p>Part number 230603N511</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21933 Bearing pair set - connecting rod<p>Part number 230603N521</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
21934 Bearing pair set - connecting rod<p>Part number 230603N531</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>