SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6ca258688f647715d8bdfb7cf114786773453351fb01a28e839d05c766e3152' 
  AND token = 'lX5XRb9+kosZKyexsmzYjVdNFHRNMjdd4chKLgqVpvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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