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 (
    8663, 8779, 8562, 8657, 8689, 8627, 8619, 
    8766, 8838, 8936, 10020, 8910, 8731, 
    10167, 8573, 8916, 8601, 8568, 8655, 
    8667, 8618, 8536, 8566, 8776, 8590, 
    8560, 8914, 8933, 8629, 8739, 8748, 
    8775, 8787, 8783, 8737, 8470, 8742, 
    8567, 8815, 8683
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00121

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 (8663,8779,8562,8657,8689,8627,8619,8766,8838,8936,10020,8910,8731,10167,8573,8916,8601,8568,8655,8667,8618,8536,8566,8776,8590,8560,8914,8933,8629,8739,8748,8775,8787,8783,8737,8470,8742,8567,8815,8683)) 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"
      ]
    }
  }
}