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 (
    10656, 10657, 10658, 10659, 10660, 10661, 
    10662, 10663, 10664, 10671, 10673, 
    10675, 10676, 10677, 10678, 10679
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00192

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 (10656,10657,10658,10659,10660,10661,10662,10663,10664,10671,10673,10675,10676,10677,10678,10679) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
10656 Protector-wiring<p>Part number 91961T1260</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10657 Protector-wiring<p>Part number 91961T1270</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10658 Protector-wiring<p>Part number 91961T1630</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10659 Protector-wiring<p>Part number 91961T1640</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10660 Protector-wiring<p>Part number 91961T1650</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10661 Protector-wiring<p>Part number 91961T1660</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10662 Protector-wiring<p>Part number 91961T1700</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10663 Protector-wiring<p>Part number 91961T1670</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10664 Protector-wiring<p>Part number 91961T1210</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10671 Bracket-junction box<p>Part number 919G5T1310</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10673 grommet<p>Part number 91981C5030</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10675 Protector-wiring<p>Part number 91961T1190</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10676 grommet<p>Part number 91981T1040</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10677 grommet<p>Part number 91981A9080</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10678 Protector-wiring<p>Part number 91961T1200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
10679 Protector-wiring<p>Part number 91961T1130</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>