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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b578e5fea808d1460e8c33ccfa3e7c3abb71a27e5b47e846b9fa5c9bf7b39ad' 
  AND token = 'dIEVsQGUExCN5hMzlrxwDTRdiFdk9oBNHW6ZkrFA+oI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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