SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '03668d811b1cc6a3cbf46f1cea838c34d6ac09950b1da1ed1a3b020d02b3afbe' 
  AND token = 'SCsW9IDJtYCZByJhMTjBuHxschdY7Rvz4DuuadOKPc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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