SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a46881aed39047809ff9fd6dc1a325bb75244d0c56859ddd8e9202bfa0ed5171' 
  AND token = 'V6JCMFyDZJJnWNCdz4mJeYiqgRgLGpYkRI6bM/e4uXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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