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 (
    89724, 88934, 83131, 90084, 89647, 89619, 
    89632, 86381, 92450, 92451, 92452, 
    92453, 92454, 92455, 92456, 89642, 
    89644, 89645, 91838, 90110, 90070, 
    89177, 92042, 92058, 92074, 92130, 
    83103, 85530, 85534, 84109
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00089

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 (89724,88934,83131,90084,89647,89619,89632,86381,92450,92451,92452,92453,92454,92455,92456,89642,89644,89645,91838,90110,90070,89177,92042,92058,92074,92130,83103,85530,85534,84109)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}