SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '373084fa1f9c441f70501609b67a423c194a0194ea3d3736c10f2caf74a5892b' 
  AND token = 'xz2yOxJVKlPzMgxAz4I4Kwlofj3IfxRx4LghNcm+eDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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