SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '', 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description, 
  cscart_product_descriptions.meta_keywords, 
  cscart_product_descriptions.meta_description, 
  cscart_product_descriptions.search_words, 
  cscart_product_descriptions.promo_text 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    6676, 6771, 6783, 6769, 6775, 6777, 6779, 
    6773, 6781
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id"],
      "key": "product_id",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 9,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (6676,6771,6783,6769,6775,6777,6779,6773,6781)",
      "attached_condition": "cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text
6676
6769
6771
6773
6775
6777
6779 <p>Crescend 5-PK Series - 764-870 MHz / 0.1-0.2W input / 80W output / 13.8 VDC / 24A max current</p><p>5-PK Series comes with one amplifier, but can accomodate up to 5 separate amplifiers that are mounted in the FPR-5 rack unit.</p>
6781
6783