SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f0f2255ea9ac7592808b92e3699217bad3d8743c6b5e8ff0489e2d4065bffbf' 
  AND token = 'kxpNOev4j/b8gCV2c7V6mbBsrLZKi6qhJpL1csK6aag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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