SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c621cdf7e72723c1c1dae1c7b536e9df9552cfc6f38cc73d2b387401106a4224' 
  AND token = 'z8dG64tsDjKzbDhIMjY4xiHUH2zsTTD3gVGfYtVJMaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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