SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712caae950e85d563643fa13f71c8ef2464ba9859182343358fc17f13a16e228' 
  AND token = '6b2SilKabDUQGr8lXvMes2sXqDTNCpaawwksUa0y+Xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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