SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a16dda28f67ca7709022ee23328e18fcf325373dfac1aded029772f9b29d9c02' 
  AND token = 'hjN04TdURFCzstqe66sYPnXCsF4Es0GGgezItdhDGt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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