SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3f7e5e685c1daec8fa6d75829913432027b139125172a4484236ea949457359' 
  AND token = 'vKKWxco4xZCjuaIqUqDOECU5Eh93Bi067llfkU6GCxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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