SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f6f5413a76b84771c50a731984c71a064e821b2a59ae2108326cda09aec32e82' 
  AND token = '+hO6WPd2B0endy6enDaAfqYCAsf8I3Az6H9nimk1gks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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