SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d9c46e710f73d6b2b7647b8c3e3fa5dc20c63564e7f58139a5c9b67483a77c' 
  AND token = 'CPi4mTXql9PR1h7HmJhNWAwzqFpQtyYvCgEECJFCq4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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