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 (
    8760, 8764, 8766, 8767, 8771, 8773, 8774, 
    8775, 8776, 8782, 8783, 8784, 8786, 
    8787, 8788, 8789
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id", "idx_product_lang"],
      "key": "PRIMARY",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 16,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (8760,8764,8766,8767,8771,8773,8774,8775,8776,8782,8783,8784,8786,8787,8788,8789) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
8760 Cover-Bell Housing<p>Part number 215143C101</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8764 Plate-baffle<p>Part number 215253N100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8766 Gasket-Water Pump<p>Part number 213543N130</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8767 Gasket-Water Pump<p>Part number 213543N140</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8771 stud<p>Part number 282573N000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8773 bolt<p>Part number 1120614706K</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8774 Bolt-flange<p>Part number 216503N001</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8775 Bolt-flange<p>Part number 216503N100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8776 stud<p>Part number 213583C100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8782 Bolt-flange<p>Part number 21892T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8783 Bracket assembly-motor mounting rear, left<p>Part number 21890T4250</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8784 Support-Hanger<p>Part number 28785T1100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8786 Support-Hanger<p>Part number 28785T1200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8787 bolt<p>Part number 554193M100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8788 Tape-Blanking Hole<p>Part number 841813L000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
8789 bolt<p>Part number 1140306306K</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>