SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9a24298dc199eb2a87c1cac9b78076bfab61230ce1f4e28323692a28b4ce1cd' 
  AND token = 'ZQdwsjJopiBsTk5kEqlHHBKIw+TKgWcCmObakjuv1KY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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