SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40ed1061f969133643939834679e9f4dea6d551e7080d6f96c92f9081ea018f0' 
  AND token = 'gfa4DjFsFOwulLBINLQnQTMPMdbElDCTO+m8HxbQgFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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