SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6f17f427e6538d99a861391d3d2f10d7d08a908dc13e3ee5e7d1785eb7bfdb4' 
  AND token = 'E3p4O+awBjPKUqoy7hZhrcp/5zgmJUE3laFOt12pxcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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