SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8b337249642b79bec48155fc217c3819f30fa18338042e05f7854bd039eab2' 
  AND token = 'HOkazcDu5JVWV03vVgBNxG3gdU4l0VvHG2jnNq3gCtU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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