SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '586cffa64fc9aedbdef79338b8139521d176ddc3e1a606712bf0f530b07b4a35' 
  AND token = 'qSDNaVnWt8NSQdVkWcmgs0rImWZp1Lbz0RWiTE9iM+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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