SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b6f0b73bd123e7d9c4738085acfa2707da0dd358a89967aa83235990745e51f' 
  AND token = 'qK45y3XynBc3QhhgRGoyiCfMej2qLkGLN5CJd0ZXhNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}