SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bcdaf4a0f8a350055adccaaa4eee4a43356e3ba0e4dd93235e552bcf377cf2a' 
  AND token = '6qUdGJl+yPeCFEnZFLbPHawfCT/XV6nKffcWPPcICXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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