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 (
    908, 3090, 2372, 2752, 1143, 2359, 2559, 
    2363, 2845, 2822, 2603, 3136, 2253, 
    2367, 2854, 2751, 2809, 2255, 2587, 
    2927, 2729, 2761, 3140, 1542, 2374, 
    2694, 3026, 3142, 853, 2812, 3096, 1540, 
    1544, 2736, 4887, 2723, 2829, 2742, 
    3556, 2251
  ) 
  AND cscart_product_descriptions.lang_code = 'ar'

Query time 0.00115

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 (908,3090,2372,2752,1143,2359,2559,2363,2845,2822,2603,3136,2253,2367,2854,2751,2809,2255,2587,2927,2729,2761,3140,1542,2374,2694,3026,3142,853,2812,3096,1540,1544,2736,4887,2723,2829,2742,3556,2251)) and (`softwarepirmam_hewadelivard_cscart_4`.`cscart_product_descriptions`.`lang_code` = 'ar'))",
      "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"
      ]
    }
  }
}