SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3a92727551d613a30c16ee3cc102a0796e9e41b9b49e6095f1b5831bdd483cc2' 
  AND token = '9zhKPJ6+G4iIbvmug9JSgxi/LWPvtWakyDMIqy0nIrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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