SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b98dcfdedb7df5fdd597795dda9b23cd126f506ae561d85d458d19e70919a85' 
  AND token = 'cyRBRlwj3mMlnVg2iRfrSowxKcCJzZGO+r7JUuXhguI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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