SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aaaed191b1585b596def0827133001eb6e5c5edc810f893768bf596af68168af' 
  AND token = 'kH1AnYOkmzBerMEj689O46FpNbK7ZT/gWh7XLWKTz54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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