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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f02afe1508084af1d6c6d2de4fafa9534f7a9daf7e35d5882470c271049d9cf' 
  AND token = '8jt6EJ8nSOmq38aMNUt8rQ2TyTZJcFIvGo2NKQhQZBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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