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 (
    3855, 3859, 5105, 8812, 6163, 6853, 6161, 
    7807, 6061, 6062, 6854, 6060, 7823, 
    7838, 7827, 6821, 7829, 7811, 7866, 
    10103, 6852, 7841, 6850, 6855, 7861, 
    7856, 10160, 7863, 7840, 7812, 7855, 
    7860, 7868, 7869, 7870, 10242, 7813, 
    7825, 8242, 8373
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00127

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "28.33"
    },
    "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": 40,
      "rows_produced_per_join": 40,
      "filtered": "100.00",
      "index_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`product_id` in (3855,3859,5105,8812,6163,6853,6161,7807,6061,6062,6854,6060,7823,7838,7827,6821,7829,7811,7866,10103,6852,7841,6850,6855,7861,7856,10160,7863,7840,7812,7855,7860,7868,7869,7870,10242,7813,7825,8242,8373)) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "24.33",
        "eval_cost": "4.00",
        "prefix_cost": "28.33",
        "data_read_per_join": "182K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}