SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '884205062fc2365496bbc628f94ecb23f831714c6b3ce1f26f973968829a31a5' 
  AND token = '/tgLECHJQOW6JWlc8vT6kOFhZoSoiN6n0dVTZLpUM9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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