SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b47999e42ff5af7374a78f6a50a49b2bfe5dd2aee78bc54b302bd97740e42dc1' 
  AND token = 'Of5KS3qAEW0IigdPUSUgMuhwRNNUdUxTyGrMPaKcrC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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