SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff3841f218e335fc64b87c5a089e948a390fe665f2e13b07bc26ae314a95d307' 
  AND token = '/cPjPRE9sxIVyY7PCOxCvyKcxdI+IXfNX5eRcucmGBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}