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 (
    19965, 19966, 19967, 19968, 19969, 19970, 
    19971, 19972, 19973, 19974, 19975, 
    19976, 19977, 19978, 19979, 19980
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00044

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 (19965,19966,19967,19968,19969,19970,19971,19972,19973,19974,19975,19976,19977,19978,19979,19980) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}

Result

product_id short_description full_description unit_name
19965 Wheel Assembly - Aluminum<p>Part number 52906T6200</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19966 Bar assembly - front stabilizer<p>Part number 54810T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19967 Arm assembly - front upper, left<p>Part number 54400T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19968 Arm assembly - front upper, right<p>Part number 54401T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19969 Lateral arm assembly - front, left<p>Part number 54500T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19970 Lateral arm assembly - front, right<p>Part number 54501T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19971 Tension arm assembly - front, left<p>Part number 54505T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19972 Tension arm assembly - front, right<p>Part number 54506T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19973 Bracket-stabilizer bar, side<p>Part number 54815T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19974 Bracket-stabilizer bar, right<p>Part number 54816T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19975 Insulator Assembly-Strut<p>Part number 54610T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19976 Pad-front spring, upper<p>Part number 54634T6000</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19977 Shock absorber assembly-front, left<p>Part number 54605T6861</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19978 Pad-front spring, lower part<p>Part number 54633D2100</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19979 Shock Absorber Assembly-Front, Right<p>Part number 54606T6861</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>
19980 Fork-front shock mounting<p>Part number 54680T6050</p><p>If you are not sure about compatibility, please contact us in advance to confirm the part number.</p>