SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fa466390cf6ad25fa397652e6cddbe4d206f77273ad0a2364f80d3a33961415' 
  AND token = '18a8MWSB50/+bmCGMAIhdKoRKiKFw7WAp7MSQZ4cvrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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