SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2f921f30c4605198445c85c36c7f246d8581df26686d771013f0430e085c91b' 
  AND token = 'gsYC16BJfNEd+ICQz2zRfFjYGClmdXQEAsEq+Pph0GA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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