SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8c59fd20afc2a097e330b3c46d637ed17cbbca08f03ec021c4eecfd1a200aab' 
  AND token = '7WIki/ge2K0XjKHoC8QsS3ONl51Jw5/xto/14RrEHGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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