SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76e50474041da2dda09c53a9f2488325bb609dd994f89e167796c2cbcbf66d55' 
  AND token = 'qunXZ+XmXgSynKibsNUNJd8xhR3B8oev3neqp/VctwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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