SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87a61beb09ee4fa541bfd082f717818a83a87d8d0a09e5da1d2cdafedcd6d900' 
  AND token = 'uMfDysE5+PtEsc0cbzrdHuAhfj9LIW0JXWGqKwxCPAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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