SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f2bd0a8c7e933280a434081ab66a53da35be5844abf45b13e5244d118392819' 
  AND token = 'jQfKzRo5vAh09+Zyx6ncGmoDdxNIvETrHhOr5ISqL8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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