SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93b9bf3c5cb9e1cf9c06006cca30786e11d0b6c8654b5cd82b2c38357f32bc86' 
  AND token = 'saFQfP6qy5hWoMyGM0AtWJKlhOQXXjlc/fklPWp300s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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