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 (
    90000, 82618, 83421, 89833, 89885, 89957, 
    91523, 86475, 86476, 86624, 86625, 
    86693, 86694, 86751, 86752, 85351, 
    86519, 86795, 83046, 83047, 90882, 
    90883, 90961, 90962, 83024, 83025, 
    90860, 90861, 90939, 90940, 82810, 
    82883, 82956, 83330, 83340, 82593, 
    82595, 83356, 83358, 91112, 91198, 
    91253, 85287, 85288, 85384, 85385, 
    85435, 85436
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00104

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (90000,82618,83421,89833,89885,89957,91523,86475,86476,86624,86625,86693,86694,86751,86752,85351,86519,86795,83046,83047,90882,90883,90961,90962,83024,83025,90860,90861,90939,90940,82810,82883,82956,83330,83340,82593,82595,83356,83358,91112,91198,91253,85287,85288,85384,85385,85435,85436)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}