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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0f71e80536fdf50a7e5745367ab41a2dcec056a3bd70353cecbc0095a4dead81' 
  AND token = 'MpY9AYEGbkpAJIVmOYqY0LnEN9IPgTKBosQ9+qVKsQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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