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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a8cd9ada2064a6b3814465fbc31ced55543d34e2fe4b96b9f24ce318e93b49c2' 
  AND token = 'kZWT9L4Fev7w7pyuqEOXqgjTzkQMmHNPA5nFSlUsFqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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