SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5904d9ce49b336a02fc6839dfbb5678cfadfb10f2f5240d69c36e0ea57c4470c' 
  AND token = '7KH1eRkoHLQf8UyUdlnGGBQ7jIIhYmoEAwCp4PvU/EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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