SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5c6cfb4ee3055975a6c4bb6f3a532a5a54198911cb1c7d7fd5203268a68c453' 
  AND token = 'Uwn6TDb/FwKKwgIe6rNx/lzXLlOwFXI42wsX2OGo7wU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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