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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, 
  cscart_product_descriptions.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (286, 285, 287, 290, 289, 288) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "lang_code"],
          "rows": 6,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (286,285,287,290,289,288) and cscart_product_descriptions.lang_code = 'en'"
        }
      }
    ]
  }
}

Result

product_id	short_description	full_description	search_words	promo_text
285		<p></p> <p>Compatible Part Number:0X3X6, CGFJT <sup class="superscript"></sup><br>Model:DPS-200PB-184<sup class="superscript"></sup></p> <p></p>	DPS-200PB-184, 0X3X6, CGFJT, S3048-ON, DELL 200W, Reverse Airflow PSU
286	<p>Optiplex 7010 9010 780 790 990 Usff</p>		1VCY4, NMPRY, DPS-200PB-191, OptiPlex 7010, OptiPlex 9010, OptiPlex 780, OptiPlex 790, OptiPlex 990, USFF 200W PSU
287	<p>Juiciness-e bhorpur ebong akare boro Giant Kew pineapple—fresh juice o smoothie-er jonno shera.</p>		Giant Kew, Giant Pineapple, Juice Anaras, Big Pineapple, Fresh Anaras
288	<p>Deshi jat-er sobcheye misti o shugondhi Honey Queen pineapple.</p>		Honey Queen, Misti Anaras, Sweet Pineapple, Deshi Anaras, Premium Pineapple
289	<p>Natural golden colour ebong Vitamin C rich MD2 Gold pineapple.</p>			<p>MD2 Pineapple, Gold Pineapple, Golden Anaras, Vitamin C Fruit, Export Quality Pineapple</p>
290	<p>Kantahin pata o cylindrical shape-er smooth texture pineapple.</p>		Smooth Cayenne, Juice Pineapple, Sliced Anaras, Canning Pineapple, Fresh Fruits