SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a4ad0d6886a036e15e309fff96dbc7c6046040ec0d47079a2cb7ddedf42be31' 
  AND token = 'MTtyqskxY/++3d41gQ9y3i1WCSZsTliXyIvS0nYgjQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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