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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8b9b94de1cc3b5d49f908d5a156700e09574b5be1623cc8183016b6c307e45ca' 
  AND token = '0qf5GcAOiiQ5a9GyV1lS9V2fUqrhJ/N2FFzPI/KjMaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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