SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '818ac6c9494e1fbe8e743a7c22ae27be9ad7b1e68ef4385398b73f67a8edf471' 
  AND token = 'dpUUEshj+hKREVWgOYtmMlMN/lWxSLLeOqTGaHQ6j9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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