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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3f03227e742f142bae9e9a7e00419e4c845af5d480ffd5de99567de1bbb96f98' 
  AND token = 'VmkzlVKLAh5ReNwcG9o/PdrBidWtkOGeWlDGChMB0kE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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