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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f6dc8ff812a55a6b32dc87312d24bd6b05ce8e3ebfc1876d42fa443793f4268' 
  AND token = 'RkNGkZRpmn8lByvd6aWd2XQZlXQ4z7pY4JhxlPa/od8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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