SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b28d4958fc455e79b7ee3336cd9461e504852e57bc7226b5ddefb9480270008c' 
  AND token = 'Vu3yoPvG0act0QQZP/Vl+Nh1PZJ3ZLdmeC8FiqwHxY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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