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 (396) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "const",
      "possible_keys": ["PRIMARY", "product_id"],
      "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
396 <p><strong>30 W Dual Zone Loud Hailer - Now with adjustable backlight</strong> </p><ul> <li>30W PA output</li> <li>Dual zone output forward, aft, or all</li> <li>Adjustable backlight</li> <li>Noise canceling microphone</li> <li>Easy push button control</li> <li>Loud speaker audio</li> <li>2 Intercom Station capable with the MLS-300i intercom speaker</li> <li>3 Year Waterproof Warranty</li> </ul> loudhailer, VLH3000, loud hailer, standard horizon hailer, standard horizon loud hailer, standard horizon loudhailer, VLH-3000, VLH-3000A, VLH-3000-A