SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd8c8ee8b899b93f2a62116c173481fe209859e542b3c1caa17c55917016064b3' 
  AND token = 'BM6IY8saSHRg42BNEGEBVwq68A03+QxK8uKFveuJU/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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