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 (3993, 3991, 3992) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00019

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": 3,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (3993,3991,3992)",
      "attached_condition": "cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description meta_keywords meta_description search_words promo_text
3991 CP185 Antenna, CP200 Antenna, CP200d Antenna, CP200XLS Antennas
3992 <p>Short, unobtrusive stubby antennas are ideal for radios worn on the belt. This rugged, 9cm stubby antenna features a capless sheath for maximum flexibility. The VHF antenna works in the 162-174 MHz range. </p> CP185 Antenna, CP200 Antenna, CP200d Antenna, CP200XLS Antennas
3993 <p>This 7-inch heliflex antenna has a one-piece finish, steel core and spiral wound conductor for optimal radiation characteristics. The VHF antenna works in the 150-162 MHz range. SKU: NAD6502AR. </p><p>Replaces the HAD9338BR </p> CP185 Antenna, CP200 Antenna, CP200d Antenna, CP200XLS Antenna, NAD-6502, HAD-9338, HAD9338, HAD9338A, HAD9338AR