SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cbeb43b25546f595f1436867b422c0eed2cb5e0d1089f621da0172ece7c716dd' 
  AND token = 'CLVYCa+zXmGMvChu4gGD/Id5jlL79VmGHZLe4bWio50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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