SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c10fcccb2b70a6d45d268ada2b97350da67443bca3c0770e95e6b37151ea130a' 
  AND token = 'nXJMzxv5LiB9Jip4Sb/kJ27b+Namk6i9RbEpMYVt+es=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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