SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a65c6a63e23ae8dbeb6fd7fb90c84182f65d34b748d3c29744f3d125c92b603' 
  AND token = 'N7h57BYqVUxWJgXl7fJSfl9+UrRw8mDpuMoSrCBxaTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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