SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5af8641f8357868ce57e037559b4473c0492e13a9a5401813db869a4709400ba' 
  AND token = 'BztZYsGCEvrd+yN1NgtrKlqTtjt6WCZk7HXNh7JFpBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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