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 (
    5378, 5383, 5379, 5381, 5380, 5382, 5384, 
    5385, 6371, 6356, 6277, 6393, 6394, 
    6332, 6362, 6392, 6354, 6331, 6337, 
    6395, 6423, 6364, 6359, 6330, 6355, 
    6396, 6372, 6398, 6358, 6365, 6361, 
    6397, 6360
  ) 
  AND cscart_product_descriptions.lang_code = 'ar'

Query time 0.00124

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "23.37"
    },
    "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": 33,
      "rows_produced_per_join": 33,
      "filtered": "100.00",
      "index_condition": "((`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`product_id` in (5378,5383,5379,5381,5380,5382,5384,5385,6371,6356,6277,6393,6394,6332,6362,6392,6354,6331,6337,6395,6423,6364,6359,6330,6355,6396,6372,6398,6358,6365,6361,6397,6360)) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`lang_code` = 'ar'))",
      "cost_info": {
        "read_cost": "20.07",
        "eval_cost": "3.30",
        "prefix_cost": "23.37",
        "data_read_per_join": "150K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}