SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc2eb13951d12804b8e3bce7b92d6c16363247d8aaffed0449af1af516274e4e' 
  AND token = 'V9FNhsu/5wgp91NrrJheIVXn2h8/nUqaQ4lRz9Zkmiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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