SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b8d61611c4dc6f72ab823c702bdc96d4563d010e96dbdd595f08ad21a347aea' 
  AND token = 'm2bWMvMHYC/xAPUZjYxvIDxuYQQ9mz40zfVVeZZXC+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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