SELECT 
  cscart_ult_product_descriptions.product_id, 
  cscart_ult_product_descriptions.short_description, 
  IF(
    cscart_ult_product_descriptions.short_description = "", 
    cscart_ult_product_descriptions.full_description, 
    ""
  ) AS full_description, 
  cscart_ult_product_descriptions.meta_keywords, 
  cscart_ult_product_descriptions.meta_description, 
  cscart_ult_product_descriptions.search_words, 
  cscart_ult_product_descriptions.promo_text 
FROM 
  cscart_ult_product_descriptions 
WHERE 
  cscart_ult_product_descriptions.product_id IN (6843, 6840, 6841, 3477) 
  AND cscart_ult_product_descriptions.company_id = 1 
  AND cscart_ult_product_descriptions.lang_code = 'en'

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "3.16"
    },
    "table": {
      "table_name": "cscart_ult_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id",
        "company_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code",
        "company_id"
      ],
      "key_length": "13",
      "rows_examined_per_scan": 4,
      "rows_produced_per_join": 4,
      "filtered": "100.00",
      "index_condition": "((`gaseus`.`cscart_ult_product_descriptions`.`company_id` = 1) and (`gaseus`.`cscart_ult_product_descriptions`.`product_id` in (6843,6840,6841,3477)) and (`gaseus`.`cscart_ult_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "2.76",
        "eval_cost": "0.40",
        "prefix_cost": "3.16",
        "data_read_per_join": "15K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "company_id",
        "short_description",
        "full_description",
        "meta_keywords",
        "meta_description",
        "search_words",
        "promo_text"
      ]
    }
  }
}