SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98f7ad7617d630bf825651445889f570398871144d1d17f2c57689406e944c6e' 
  AND token = 'wP+7MJJWqEVGw8w8/ldcvzJpu8LKPiStpibaNGMPYRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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