SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5946f57cda5685c7ef2f83945b036f5f134530ed8ba9679ede295839ab06e613' 
  AND token = 'JWlHvj9aGVIi7RYcm478AehdjyuXaIy+wzHwGzCPuKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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