SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f11821349f6fcd382858b99bead476e51be4e81b692da398357e875917c69b1a' 
  AND token = 'GZxrir8kyBoOv9yXqnCJYFXTwZGaRVMcIkZwPnqDgJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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