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 (
    93845, 94119, 94120, 94121, 94122, 94123, 
    94124, 94125, 94126, 94127, 94128, 
    94129, 94130, 94131, 94132, 94133, 
    94134, 94135, 94136, 94137, 94138, 
    94139, 94457, 94619, 94620, 94621, 
    94622, 94623, 94624, 94625
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00064

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 (93845,94119,94120,94121,94122,94123,94124,94125,94126,94127,94128,94129,94130,94131,94132,94133,94134,94135,94136,94137,94138,94139,94457,94619,94620,94621,94622,94623,94624,94625)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
93845
94119
94120
94121
94122
94123
94124
94125
94126
94127
94128
94129
94130
94131
94132
94133
94134
94135
94136
94137
94138
94139
94457
94619
94620
94621
94622
94623
94624
94625