SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b4bb1d3c3d7775daccc95e5f0782d2cdeba0c445e6b0c04e4a43fd5838f2f06f' 
  AND token = '3h91YokxKMNvGl4z+jAkwE9CN/+c8jtfxYUBYPxpweA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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