SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdadd889684f81f36f8a4418f5b2b2564aefa0c858d5eddbea5c7206dee3635a' 
  AND token = 'cKiJnP2zgSSid9M+vYDsvLj/9o8BHGZGnuOFIVKp/D8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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