SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b9b2914f4a37e18f523efc3ab2605f49883103e0268333d0ae96521f00bd3cd' 
  AND token = 'uYx/Me5sKc7zSvVGn0rxHNVq5Hy6YBvvmFEvcQPtBeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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