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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 (85) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00029

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
85	The root beer scent, also associated with birch beer and sarsaparilla, comes from essential oil of white birch. The hint of wintergreen is also from birch. Ground sassafras root and bark is added to the bar to lightly exfoliate the skin. The sassafras also makes the bar a lovely purple shade. Like all Herbaria soaps, Sassafras Birch is first and foremost a great soap with terrific lather and moisturizing hemp seed oil.		Sassafras Birch soap	"Smells like root beer!" With moisturizing hemp seed oil. Buy 6 get 1 free. Over 60 varieties healthy for face and body.