SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90286bac0addcfc2041ab7b3ab8087fa60135f50f9a41e5e84a0629a66305707' 
  AND token = 'QMG9S8qyHvHXbumBpcYBrc5Z+VH6+HTMYNJJPz3LwVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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