SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd12f636cf0d1ba86f08a7f41b0303ea5866a275bde30234cfcfc761f60b6691' 
  AND token = 'SriWsuh9AksqRpiDXLJlrdvGVDFUMJKdvN79ZTHVZWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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