SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '267f5bb99435b6aadd59bcc767a454b5cc4ff8494c42701911ddd6586af120e5' 
  AND token = 'f0P5mhK+GoMIUvIWWB/rdFHlfas8Mh3PjbCToeyDYuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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