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 (4148, 4149) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00018

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": 2,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (4148,4149)",
      "attached_condition": "cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text
4148 <p>This alkaline battery frame allows you to use AA batteries, in emergency situations. Provides up to 26 hours of battery life.* </p><p>(*Battery save feature must be activated for optimal battery life.) </p> CP110 Battery
4149 <p>This ultra high-capacity Li-Ion rechargeable battery provides up to 26 hours of battery life per full charge on 2-Watt models, and up to 18.5 hours per charge on 4/5 Watt models.* </p><p>*Battery save feature must be activated for optimal battery life. </p> RLN6308A, RLN6308B, RLN6308C, cp110 battery, cp-110 battery, cp 110 battery