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 (
    5665, 5662, 5666, 5669, 5661, 5667, 5664, 
    5668, 5663, 6206, 6205
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00026

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": 11,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (5665,5662,5666,5669,5661,5667,5664,5668,5663,6206,6205)",
      "attached_condition": "cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text
5661
5662
5663
5664
5665 <p>100A Terminal Fuse</p>
5666
5667
5668 <p>Class T Repl Fuse / 400Amp</p>
5669 <p>DC Class T Fuse Block</p>
6205
6206