SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3012d67896620c9f4bfaef8513c32a8259ec234abd8afbb73523da480f3698f' 
  AND token = 'JsUcJRpMnJs33pgy4KCx9OGtk5hF47AWMpsCvXj0wN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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