SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d3ac012cfa87627df7bbf61d7414295ac98d740d23e76ec463db805758e9f11' 
  AND token = 'kCIriRsZxSLS0dQTLeR7ULSBeYxBZydocdxrSXcj3W0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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