SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0fc4ce261b668c5001d120933d4eb06bf7356f20538f6c51a35096b505d803ab' 
  AND token = 'XIRd60eOEiDdOw+HYvfJH28lDjXZ8jEIxHyiZ206NiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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