SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3a52509eb1c25a406c36406bc9e34785145c5b13a441fab3b1e716986aaa9e3' 
  AND token = 'NuXtts+WPHeHngvFiTsG8IKWkyfM7VtZs1hg5Qrw+1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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