SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3de96cc7b81609ec7576c769e5f30df842bfbfd6fc92be0df7781d484ee4292c' 
  AND token = 'JmxLlQX0elpmdjd1cYDpqIEZMEUojwwwpKWOz+sir+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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