SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a99364cd403b749509e74124456effd158f1f4c04cd0c641b6f3a53c50918c36' 
  AND token = 'SK+rXtDdIuoIspJm7VvNlIY4JZYKGqnWhxvqA/iezg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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