SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad3ce973ea5659a258941cca95e9b449c60bc0f604cb30196e9c60864845b7c4' 
  AND token = '6yj7d1qfQ/OqRGouBgNPgF3m136Xh7NaMBF90sNjdYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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