SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c874ea9bf712ea6d9046eed4991f9a931da4385b5809e981e90ba3e5bf7cc3c9' 
  AND token = 'WDApPSAuTCnTkKH3BwVWEbFjv0W5lWCLlLqaj+vQEyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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