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 (
    94756, 94757, 94758, 94759, 94760, 94761, 
    94762, 94763, 94764, 94765, 94816, 
    94950, 94951, 95565, 95566, 95567, 
    95568, 95569, 95570, 95571, 95572, 
    95573, 95574, 95575, 95576, 95577, 
    95578, 95579, 95580, 95581
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00069

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (94756,94757,94758,94759,94760,94761,94762,94763,94764,94765,94816,94950,94951,95565,95566,95567,95568,95569,95570,95571,95572,95573,95574,95575,95576,95577,95578,95579,95580,95581)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
94756
94757
94758
94759
94760
94761
94762
94763
94764
94765
94816
94950
94951
95565
95566
95567
95568
95569
95570
95571
95572
95573
95574
95575
95576
95577
95578
95579
95580
95581