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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1de99ace0a18bbb7da5daf5ab8f139fe363237721a81d224b4da9dc1df3eb44' 
  AND token = '68hvTPdYzhoJRYyQbAApXXnLtTsxWqwEIgBhm2dLJhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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