SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9a4f676d56b75f62a9ae2e1f0b27cc3e94e3d288f6e435b0058d0621248fe82' 
  AND token = 'djsmWxSRY9wqk4GgmKIoUUoSkQ2AlYLWXa+gsQ7V3iM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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