SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cc8ca1f924c006d83161d48744a3ec34ada7776d585b6e19821d3d7884ed560' 
  AND token = '7VqfyYYwHRmhR+R/QMeBAnYzPuwgvDQmh7N4msoLlqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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