SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4662621913a35ba9923293cf48174f9baf590e1e270bcf30ae3d2909e0dbbfe' 
  AND token = 'dLiFzOjfc4F83TTve+eUaroY/WO/Mb3Dc0eWQesA6WA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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