SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af755d668f6d625848f8aef2aeaa5a7687d1f535719fad898d50a7e167c6d27a' 
  AND token = 'PcNAAluR7q8TBdXZvVvPyCdbsqR4//XMG0sfB8FtKZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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