SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd21910cdf577ca15cd46d83a6dd655995654322c9012545b963b8d2f1503dc2b' 
  AND token = 'z98v1yTN8tcFPFujeBJ4N+WMPhQQZxKM+u4fSGvCJjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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