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.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 (1581) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "const",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "ref": ["const", "const"],
      "rows": 1,
      "filtered": 100
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text
1581 Herbaria all natural lip balm Lip Balm, all-natural, vegan Soothe chapped, cracked lips with Herbaria Lip Balms: Almond, Chai, Chocolate Peppermint, Eucalyptus Mint, Mocha, Vanilla. Vegan with coconut oil, cocoa butter, mango butter, palm kernel oil, candelilla wax, vitamin E. Free shipping on orders over $60. <span style="font-family: georgia, palatino, serif; font-size: 14pt; color: #008000;">Eight Varieties including Unscented</span>