SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '356883a1d3a23dcbb94f5e41fa6ab3dce9a6521d8467b143234d366120fc9aea' 
  AND token = 'ZmLWiuQ59LjU+WSVuwyQNLp1lqzRFcYwDp7K7/XxPvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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