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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 (3820, 3821, 3818, 3819) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00022

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 (3820,3821,3818,3819)",
      "attached_condition": "cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id	short_description	search_words
3818	<ul> <li>16 Channels</li> <li>2 Programmable Buttons</li> <li>Small Size and Light Weight</li> <li>UHF: 450 - 470 MHz</li> <li>Output Power: 4W</li> <li>12.5 /25 kHz Channel Spacing</li> </ul>	bpr-40 radio, bpr40 radio, bpr 40 radio
3819	<ul> <li>16 Channels</li> <li>2 Programmable Buttons</li> <li>Small Size and Light Weight</li> <li>VHF: 150 – 174 MHz</li> <li>Output Power: 5W </li> <li>12.5 /25 kHz Channel Spacing</li> </ul>	bpr-40 radio, bpr40 radio, bpr 40 radio
3820	<ul> <li>8 Channels</li> <li>2 Programmable Buttons</li> <li>Small Size and Light Weight</li> <li>UHF: 450 - 470 MHz</li> <li>Output Power: 4W</li> <li>12.5 /25 kHz Channel Spacing</li> </ul>	bpr-40 radio, bpr40 radio, bpr 40 radio
3821	<ul> <li>8 Channels</li> <li>2 Programmable Buttons</li> <li>Small Size and Light Weight</li> <li>VHF: 150 – 174 MHz</li> <li>Output Power: 5W </li> <li>12.5 /25 kHz Channel Spacing</li> </ul>	bpr-40 radio, bpr40 radio, bpr 40 radio