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 (
    7824, 8261, 8302, 8301, 7660, 7662, 7446, 
    7822, 7821, 9719, 8530, 8532, 8854, 
    8948, 9847, 8860, 8861, 8857
  ) 
  AND cscart_product_descriptions.lang_code = 'ar'

Query time 0.00115

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "12.75"
    },
    "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": 18,
      "rows_produced_per_join": 18,
      "filtered": "100.00",
      "index_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`product_id` in (7824,8261,8302,8301,7660,7662,7446,7822,7821,9719,8530,8532,8854,8948,9847,8860,8861,8857)) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`lang_code` = 'ar'))",
      "cost_info": {
        "read_cost": "10.95",
        "eval_cost": "1.80",
        "prefix_cost": "12.75",
        "data_read_per_join": "82K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}