SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16a02a9bd4d97a58e289968b241b55e88bc9dd807d4fc34cb18d2c1b43ba5b4a' 
  AND token = 'Au3iJ77pp3vsqIamJfYxdPocL8iCDiHyajkUwoWhJbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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