SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b19d50b35f85592634d14435d1452e1ced356fb608b57029efd87f2334c54bd' 
  AND token = 'TxaxndM3VcJmMJMbhYCRDnm72IfwaJ5gVJznAwFSIDI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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