SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26bd719f96f34638b51b7c12f59fd18c084446d81a249a4f364e6eaf0cabb87e' 
  AND token = 'jGJRdLk3fw+ZfFqqlneDpFn+X/z+ihGSh8jdsUwclmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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