SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '021cfb03373b7ad61c3fa810441a460a6b9447bd97adf700e88deb73f66de0bf' 
  AND token = 'OVQRzMF2CBQBLtSxT+owVNgR3BYTy4PZjODYDYdXfQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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