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 (
    99630, 99631, 99632, 99633, 99634, 99635, 
    99636, 99637, 99638, 99639, 99640, 
    99641, 99642, 99643, 99644, 99645, 
    99646, 99647, 99669, 99670, 99671, 
    99672, 99673, 99674, 99675, 99676, 
    99677, 99678, 99679, 99680, 99681, 
    99682, 99683, 99684, 99685, 99686, 
    99687, 99688, 99689, 99690, 99691, 
    99692, 99693, 99694, 99695, 99696, 
    99697, 99698
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00091

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 (99630,99631,99632,99633,99634,99635,99636,99637,99638,99639,99640,99641,99642,99643,99644,99645,99646,99647,99669,99670,99671,99672,99673,99674,99675,99676,99677,99678,99679,99680,99681,99682,99683,99684,99685,99686,99687,99688,99689,99690,99691,99692,99693,99694,99695,99696,99697,99698)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}