SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5651416cb4b8e55b4d00558060f096733381a387208d20a3686cd669df102cfa' 
  AND token = 'SFJUkJRE5PQzYjolD+itORlpnHzmh1ZZlic5LmaHT2w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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