SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de38d8c3b6946512c628c31c7d1804e03a8eaa54cf169dbe517c9a84da417e25' 
  AND token = 'NRP+gW4M9R5RSdQ3YUOGyxCOeFLdkCnXeQqHK5XN+wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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