SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03274022e76a82f8592a52f191394f6565703eb818d8839010125513c0dc3798' 
  AND token = 'WpEJTtJfYhiPjl88P5D6UoPlYOGFUAuBbzRvK23ZKrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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