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 (
    1909, 1145, 1127, 1126, 1125, 1124, 1123, 
    1111, 1110, 1109, 1108, 1107, 1053, 
    1051, 1050, 1049, 1048, 960, 959, 958, 
    957, 941, 940, 939, 929, 928, 927, 919, 
    918, 917, 517, 516, 515, 424, 423, 422, 
    421, 420, 419, 373, 351, 350
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00059

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "29.41"
    },
    "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": 42,
      "rows_produced_per_join": 42,
      "filtered": "100.00",
      "index_condition": "((`wearethehelpful_scalesta_net`.`cscart_product_descriptions`.`product_id` in (1909,1145,1127,1126,1125,1124,1123,1111,1110,1109,1108,1107,1053,1051,1050,1049,1048,960,959,958,957,941,940,939,929,928,927,919,918,917,517,516,515,424,423,422,421,420,419,373,351,350)) and (`wearethehelpful_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "25.21",
        "eval_cost": "4.20",
        "prefix_cost": "29.41",
        "data_read_per_join": "191K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}