SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83a0c079f7730539765141a3308cd7974f32aed47d8069185711ebcade22af46' 
  AND token = 'aVItXDPB9fXtsKCurTYbpBWL8prjEYEGV8/WVlB64vQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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