SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0df7f931e1ca1013dad6f0305beae60c433258cb77845dcdd96139f7a625cfc4' 
  AND token = 'we8r+pNWm2grtAkBlnDqpAvGa+TylWRuXN10dVlB9MQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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