SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16403d3f399eac9a03d36c2037d9756fd516f5e988fbd488439fa76f4138553e' 
  AND token = 'Q9gxOqsAUZ3ns3uLD8BxFFWDndWMQMBkrG9hfy7fARQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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