SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '39a95bcc898fb460c579f80abafda6c99f59ec602595c41ad98c905ab7803dab' 
  AND token = 'zX1bYPMo8BcuTZ2imL9j8TFpqED2WX11HFtB1ToiX7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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