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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    2114, 2113, 2110, 2111, 2112, 2109, 2106, 
    2107, 2108, 2105, 2091, 2068
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "8.41"
    },
    "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": 12,
      "rows_produced_per_join": 12,
      "filtered": "100.00",
      "index_condition": "((`wearethehelpful_scalesta_net`.`cscart_product_descriptions`.`product_id` in (2114,2113,2110,2111,2112,2109,2106,2107,2108,2105,2091,2068)) and (`wearethehelpful_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "7.21",
        "eval_cost": "1.20",
        "prefix_cost": "8.41",
        "data_read_per_join": "54K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description",
        "unit_name"
      ]
    }
  }
}

Result

product_id short_description full_description unit_name
2068 <p>dffd</p>
2091
2105 <p>vdfbfbngf vgfbngfngf 546</p>
2106 <p>vdfbfbngf vgfbngfngf 546</p>
2107 <p>vdfbfbngf vgfbngfngf 546</p>
2108 <p>vdfbfbngf vgfbngfngf 546</p>
2109 <p>Test Variant product again </p>
2110 <p>Test Variant product again </p>
2111 <p>Test Variant product again </p>
2112 <p>Test Variant product again </p>
2113 <p>Book</p>
2114 <p>tsirt34</p>