SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0365a3bbb55690f75f2271bd05846cb6d4c1faa5a023425a90da65e289421ef' 
  AND token = 'RGoZYpDgXnSxzBDTYOp5QiAZv8zl+4ph8UgWg/vP95g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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