SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d512cdebed7714ddf57546c94f847f4349b914ff329b831400419d618c5f008' 
  AND token = 'z8RzRU026Nldsi1l6yagqL4uR1eoe/HZt+WtpEIpKvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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