SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b884809cefe00ca8e4ad73442aa16b2312265f38f54346f13874eab6a2d069bc' 
  AND token = '+KNbwjmhA3ig584JlsUuUJiveWZumGinvNQMeEXeQsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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