SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '272277e9d7ce3efe60215c2a3c8d132e7ed617638de2615596d5d8c5c0b43f64' 
  AND token = '3RNjC+RFpszdD/zNbMiHoyuT5fkpfHtr1AsYSY0Wl+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}