SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12fbfcd6841751146bee6d7162d3adfe75d93edf2f77808d8216d033d8850e2f' 
  AND token = '2S9BzN51XHdEF/bLXCxe2pZgw67+N1vRqw/RGVO+LJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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