SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c936cd6a661587d8631899dea3f2b736ffaa2f4a12746d607f1cb2ce3de9cd1a' 
  AND token = 'pPZLOJPSwwDszN8TYF6kHqzLNxRa+0Zy4Vb/GLnldHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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