SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af3d4e86272e2a6d203e5e9fd70207eed1e169bdabeff854da99054102d10d61' 
  AND token = '3/wuL5R85IY/aa3QsCSPMSDi/H1l9dxKZAu5D57HTI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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