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 (
    93956, 94838, 95004, 95005, 95006, 95007, 
    95008, 95009, 95046, 95047, 95048, 
    95057, 95058, 95059, 95060, 95061, 
    95062, 95066, 95067, 95068, 95328, 
    95329, 95330, 95344, 95345, 95346, 
    95349, 95352, 95358, 95359
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00034

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 (93956,94838,95004,95005,95006,95007,95008,95009,95046,95047,95048,95057,95058,95059,95060,95061,95062,95066,95067,95068,95328,95329,95330,95344,95345,95346,95349,95352,95358,95359)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
93956
94838
95004
95005
95006
95007
95008
95009
95046
95047
95048
95057
95058
95059
95060
95061
95062
95066
95067
95068
95328
95329
95330
95344
95345
95346
95349
95352
95358
95359