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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 (4726, 4740, 4739, 4928) 
  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": "range",
      "possible_keys": ["PRIMARY", "product_id"],
      "key": "product_id",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 4,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (4726,4740,4739,4928)",
      "attached_condition": "cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id	full_description	search_words
4726	<p>This carrying accessory is a spring-action 2.5-inch belt clip for two-way radios. </p>	APX 1000 Case, XPR 7380 Case, XPR 7350 Case, XPR 3500 Case, XPR 3300 Case, APX 4000 Case, APX 4000XE Case, XPR 7550 Cases
4739	<p>2.5" replacement leather swivel belt loop for leather carry cases. This swivel latch system allows the radio to swing freely from side to side.</p>	XPR 3300 Case, XPR 3500 Case, XPR 7350 Case, XPR 7380 Case, XPR 7550 Cases
4740	<p>3" replacement leather swivel belt loop for leather carry cases. This swivel latch system allows the radio to swing freely from side to side.</p>	XPR 3300 Case, XPR 3500 Case, XPR 7350 Case, XPR 7380 Case, XPR 7550 Cases
4928	<p>Silent alert vibrating belt clip for use with PMNN4488A battery</p>	PMLN-7296, PMNN4488, PMNN-4488, PMNN4488A, PMNN4488B, PMLN7296A, PMLN7296-A, vibra alert, vibra clip, vibrating clip, silent clip, vibrating belt clip