SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e5aacc7821324b8b98e98ee0e195026890fff5a590f58b951015d290ba0d7ae' 
  AND token = 'gqK37GiatUix0vC8VZtfstEWLVh3aI9sd2MpDNXIULk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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