SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ee564d76a0af06ef28d045f7d8b51ee5d8b32f99b8963996a068860910ecd522' 
  AND token = 'gvxAasbTZglHlzHs14UVgpLrm+BskjInVkyQ1Uf/wp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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