SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92b79d9b5ff369325cc3e6b488b478a253b71e2035e278da4d5ab44fcfcf1ab3' 
  AND token = 'KUV2ekr4MOnXBRaMDkGJCe3UgRTmVvBw6vHaWF0hL8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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