SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b835c406bfaef65550cd9c0362ec3466c97afd38f93907855a823248efdf818c' 
  AND token = '2p0I180PJtuzddjQniD5+hjn6JDlWVesRV6AL+m/L7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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