SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f7539f47f53e65e781580bb488ff345345c6500462a04d80241cac0a4e02eac' 
  AND token = 'UfLaoAjAQT0l4M97VEK+rv1R7bugx6CGUSnaKzys2i0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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