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 (
    90699, 90703, 90707, 90640, 90641, 90649, 
    90683, 90689, 90733, 90842, 90625, 
    90631, 90596, 90597, 90602, 90603, 
    90708, 90710, 90682, 90688, 90624, 
    90630, 90696, 90697, 90701, 90705, 
    90673, 90679, 90638, 90639, 90647, 
    90615, 90621, 90672, 90678, 90651, 
    90686, 90614, 90620, 90628, 90694, 
    90695, 90636, 90637, 90645, 90663, 
    90669, 90605, 90611, 90662, 90668, 
    90604, 90610, 90650, 90676, 90692, 
    90693, 90653, 90659, 90618, 90634, 
    90635, 90643, 90595, 90601, 90652, 
    90658, 90594, 90600, 90666, 90608, 
    84041, 84232, 84044, 84235, 90656, 
    84236, 90598, 84043, 90048, 90049, 
    90050, 90051, 90052, 90053, 84040, 
    84231, 84234, 88316, 88100, 90018, 
    90019, 90020, 90021, 90032, 90033
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00175

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "43.24"
    },
    "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": 96,
      "rows_produced_per_join": 96,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "33.64",
        "eval_cost": "9.60",
        "prefix_cost": "43.24",
        "data_read_per_join": "366K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (90699,90703,90707,90640,90641,90649,90683,90689,90733,90842,90625,90631,90596,90597,90602,90603,90708,90710,90682,90688,90624,90630,90696,90697,90701,90705,90673,90679,90638,90639,90647,90615,90621,90672,90678,90651,90686,90614,90620,90628,90694,90695,90636,90637,90645,90663,90669,90605,90611,90662,90668,90604,90610,90650,90676,90692,90693,90653,90659,90618,90634,90635,90643,90595,90601,90652,90658,90594,90600,90666,90608,84041,84232,84044,84235,90656,84236,90598,84043,90048,90049,90050,90051,90052,90053,84040,84231,84234,88316,88100,90018,90019,90020,90021,90032,90033)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}