SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cf719f09d211cbd99da690a79cf71597788a03e792e429783b002db57c058bf1' 
  AND token = '+o2xhmQsJygD8v/HQGKzT825liUXVqeQbpJ/tveCeYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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