SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ee62255cb4b03f018af5b89cde0901db5c491a843b4d12efd0945c4a48fa6ed' 
  AND token = 'c6TSKJmbLwZkrqIzu+K0nTUlff7+gmutsrlWVKVJKY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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