SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68e4de744766869b4d7c8909ee8b4bac2e39dda815c912a45c57344bda697f84' 
  AND token = 'wEFogjnxuujJXxzMR4MzVPKGa+pSpzEV8AzhNZI6lJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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