SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '471048bcd878307b9b1cd7aec8b124cadea6248aead047f0a944310174895333' 
  AND token = 'ItYgfXcOy9lpMAgvIhfItRWFNbhPXYiNxlfb4w3VpBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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