SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b8b02cc3e14dadc8889f52484aff1d6bb0a41658ec50a3373be027493f7ac56' 
  AND token = '+qqMP2+N/dcvXKPR7rOgTlRjzq0ugy0+Y6XmZ8+owhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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