SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c03a7cb17073d185fb1f10da29c68a49a55a9e1625a320ac5702b535d6ca0306' 
  AND token = 'UvY+EvFyIfz6bH1H4coBzLIFSk/ryNU1Qs8uyHSS2f0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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