SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5010f5a917b3c2d276272949fdf442b397b9e8af66c9e705ffc65d19fccfc33b' 
  AND token = 'sOvaeG76LZU6ZsvK7nkxEzXXFbOFbFGm+BWtfS+EhLs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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