SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff5fee6194cef8eba85033c81fb43939241f042fbeea9435bddf21d0198a3d59' 
  AND token = 'IXgmRQL1dBWk7HXf2/YAWDlf/vv9zcrlj2eRZliBDW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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