SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56d65d4e2d3fbc71bb315813b4494aee863287c8f2ff7cb469fe7559be3daaec' 
  AND token = 'Kx9eQUhudAi9DTHel0BlOKvoYL35x9DWIoP6px1etdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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