SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15a0205eb7eaa785b324f82a0da34794ec57c9f8f35c82cadf82d9a09e7ad627' 
  AND token = 'j+urgoesR9VTmi6agKTdMKs3Os+LWgFkO8YiveaZRF0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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