SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b67687adf10a03cdc0ec04cabb7580425ba87b165ac119effdd3b01959a83c60' 
  AND token = '+zPmKNnBv7OdZuvTCt7jz/Py99zVdnUxgFDFN/BbZXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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