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 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    101467, 101468, 101469, 101470, 101471, 
    101472, 101473, 101474, 101475, 101476, 
    101477, 101478, 101479, 101480, 101481, 
    101482, 101483, 101484, 101485, 101486, 
    101487, 101488, 101489, 101490, 101491, 
    101492, 101493, 101494, 101495, 101496
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00070

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (101467,101468,101469,101470,101471,101472,101473,101474,101475,101476,101477,101478,101479,101480,101481,101482,101483,101484,101485,101486,101487,101488,101489,101490,101491,101492,101493,101494,101495,101496)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}