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 (
    20957, 20958, 20959, 20960, 20961, 20962, 
    20963, 20964, 20965, 20966, 20967, 
    20968, 20969, 20970, 20971, 20972
  ) 
  AND cscart_product_descriptions.lang_code = 'ru'

Query time 0.00045

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 (20957,20958,20959,20960,20961,20962,20963,20964,20965,20966,20967,20968,20969,20970,20971,20972) and cscart_product_descriptions.lang_code = 'ru'"
    }
  }
}

Result

product_id short_description full_description unit_name
20957 Sensor Assembly - Accelerated Crash<p>Part number 95920T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20958 Sensor Assembly - Accelerated Crash<p>Part number 95920T1500</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20959 Module & Sensor Assembly-Lane<p>Part number 96000T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20960 Cover Assembly - Multi-Sensor<p>Part number 96030T1000NBD</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20961 Cover - Multi-Sensor Blanking<p>Part number 96032T1000NBD</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20962 Unit assembly - mood lamp<p>Part number 92900T1001</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20963 Unit assembly - front radar<p>Part number 99110T1110</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20964 Unit-Front View Camera<p>Part number 99211T1110</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20965 Unit Assembly - Front View Camera<p>Part number 99250T1010</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20966 T/M control unit<p>Part number 954404J910</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20967 Bracket-transmission control module<p>Part number 954424J910</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20968 Module Assembly - ECS<p>Part number 95610T1100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20969 Antenna Assembly - Combination<p>Part number 96210T1550EB</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20970 nut<p>Part number 96217D3000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20971 Antenna Assembly-Wireless<p>Part number 96240T1000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
20972 Feeder cable-antenna main NO.1<p>Part number 96220T1070</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>