SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f068056229f5f4202208dd669bad7bc56b8ea2a9ec6843e9b3622b8a1e8bfca' 
  AND token = 'iMl/0qr3bJHdQyrhUIm42tzRyvJWauma1kKHLj7AUjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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