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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 (242, 243) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00027

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	cscart_product_descriptions	range	PRIMARY,product_id	PRIMARY	9		2	Using index condition

Result

product_id	short_description	full_description	meta_keywords	meta_description	search_words	promo_text	unit_name
242		<p>With 160GB of storage, iPod classic can hold up to 40,000 songs, 200 hours of video, or 25,000 photos.** That’s more than enough room for a day’s — or a lifetime’s — worth of entertainment.</p>				<p class="product-promo-text"><span class="product-promo-header">FREE US shipping over $100!</span><span class="product-promo-body">Orders within next 2 days will be shipped on Monday</span></p>
243		<p>With 160GB of storage, iPod classic can hold up to 40,000 songs, 200 hours of video, or 25,000 photos.** That’s more than enough room for a day’s — or a lifetime’s — worth of entertainment.</p>				<p class="product-promo-text"><span class="product-promo-header">FREE US shipping over $100!</span><span class="product-promo-body">Orders within next 2 days will be shipped on Monday</span></p>