SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '391a682178e884db29b6c67ca43fd040363e5d29b7d719a30a595203677cfaac' 
  AND token = '8Qr/MHXkXgvn8d6+vqsGkUG2o0wDYUJjY8eYQMuE+qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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