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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '914465daded83d9dbb68efae90ad9a480fc836cf17c66d7ec027e28eafb86cfb' 
  AND token = '50B3gEmLpnGssg5DHvQcN0qroeA0jkzCXiqhGFQf5Y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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