SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '401971e608c09203f60ebd1b09577caaaaf2d8b5fc0221f22df564b904cef4a8' 
  AND token = '/TQ15/C9ZMZvxKQa8sTVKIsFPEDC7GFido2wPfndRlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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