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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    84542, 84607, 84608, 84671, 84672, 84645, 
    84524, 84590, 84338, 84339, 84326, 
    84539, 84605, 87392, 87393, 84343, 
    84344, 84627, 87390, 84540, 84606, 
    84513, 84579, 84670, 87405, 84342, 
    84341, 86753, 86754, 87401, 84495, 
    84561, 87399, 84538, 84604, 84340, 
    84315, 86804, 86805, 84297, 85662, 
    85682, 85694, 85706, 87431, 85658, 
    85667, 85687
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00087

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (84542,84607,84608,84671,84672,84645,84524,84590,84338,84339,84326,84539,84605,87392,87393,84343,84344,84627,87390,84540,84606,84513,84579,84670,87405,84342,84341,86753,86754,87401,84495,84561,87399,84538,84604,84340,84315,86804,86805,84297,85662,85682,85694,85706,87431,85658,85667,85687)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}