SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '573ec2bc4b5fa151121c235eaac38f821357610d2d59ae3141c0a4cb97af94d5' 
  AND token = 'gakoWFHk741j2hiDwh376QbdkDyNrIvkIzUlSTMLvfo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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