SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0657ae72c82fd53211496884372e3395ffb8425e386d74407071884351a6996' 
  AND token = 'LPiUiPySlGMe69TKaTizvhAAiBJfuvc4qcD+ChbXXKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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