SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c15259a4308f5cdd92ae95f65db7605a2a7b775b1d7d8c1566fd46d9b9c51ef8' 
  AND token = '4+lj59CPN+Kz4fqmdq7Gp/bIYI+LusFRzr+uNu8Tcl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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