SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a03c0821c57018414704e1578d471cabf472f4347411f8b51a1cb98bec23b0bf' 
  AND token = 'REpfCW4HgjJoZ/yDt/n8R8ZNG6TzdwfZBSCfIwt+33c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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