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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.unit_name 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (199) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00127

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "const",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "lang_code"],
          "ref": ["const", "const"],
          "rows": 1,
          "filtered": 100
        }
      }
    ]
  }
}

Result

product_id	short_description	full_description	unit_name
199		<div class="wiki_section" style="margin-bottom: 15px; line-height: 18px; color: #3b3b3b; font-family: 'Gill Sans MT', tahoma, arial, sans-serif; font-size: 12px; text-align: left; background-color: #ffffff;">Диск: 1</div><div class="wiki_section" style="margin-bottom: 15px; line-height: 18px; color: #3b3b3b; font-family: 'Gill Sans MT', tahoma, arial, sans-serif; font-size: 12px; text-align: left; background-color: #ffffff;"><ul class="wiki_list"><li class="wiki_listitem">1. 3 O'Clock Blues</li><li class="wiki_listitem">2. Blind Love</li><li class="wiki_listitem">3. She's Dynamite</li><li class="wiki_listitem">4. You Know I Love You</li><li class="wiki_listitem">5. Please Love Me</li><li class="wiki_listitem">6. Story Fom My Heart And Soul</li><li class="wiki_listitem">7. The Woman I Love</li><li class="wiki_listitem">8. Neighborhood Affair</li><li class="wiki_listitem">9. When My Heart Beats Like A Hammer</li><li class="wiki_listitem">10. Every Day I Have The Blues</li><li class="wiki_listitem">11. Love You Baby (Take A Swing With Me)</li><li class="wiki_listitem">12. Ten Long Years</li><li class="wiki_listitem">13. You Upset Me, Baby</li><li class="wiki_listitem">14. Boogie Rock (House Rocker)</li><li class="wiki_listitem">15. Crying Won't Help You</li><li class="wiki_listitem">16. Bad Luck</li><li class="wiki_listitem">17. Did You Ever Love A Woman</li><li class="wiki_listitem">18. You Don't Know</li><li class="wiki_listitem">19. Sweet Little Angel</li><li class="wiki_listitem">20. On My Word Of Honor</li></ul><br />Диск: 2<ul class="wiki_list"><li class="wiki_listitem">1. Be Careful With A Fool</li><li class="wiki_listitem">2. Please Accept My Love</li><li class="wiki_listitem">3. Days Of Old</li><li class="wiki_listitem">4. Worry, Worry</li><li class="wiki_listitem">5. Confessin' The Blues</li><li class="wiki_listitem">6. Sweet Sixteen Parts 1 & 2</li><li class="wiki_listitem">7. Ain't Nobody's Business</li><li class="wiki_listitem">8. Walkin' Dr. Bill</li><li class="wiki_listitem">9. My Own Fault</li><li class="wiki_listitem">10. You Done Lost Your Good Thing Now</li><li class="wiki_listitem">11. Downhearted (How Blue Can You Get?)</li><li class="wiki_listitem">12. I'll Survive</li><li class="wiki_listitem">13. Mashed Potato Twist</li><li class="wiki_listitem">14. Down Now</li><li class="wiki_listitem">15. Peace Of Mind</li><li class="wiki_listitem">16. That Evil Child</li><li class="wiki_listitem">17. Blues Stay Away From Me</li><li class="wiki_listitem">18. Rock Me Baby</li><li class="wiki_listitem">19. Miss Martha King</li><li class="wiki_listitem">20. When Your Baby Packs Up And Goes</li></ul></div>