SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c929119cfdf8d8b9e7dad2496d642b26f83f038725908f971fa53e94aff80d4' 
  AND token = 'lKT+f9jQUNWZvoMrq7qm5+yUuLiUY3Jkr0PGui0wlSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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