SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b344b2d7af5f31a47a2ae6383f59c5b402caf9bc149deaf1266e26dabf881a15' 
  AND token = '3j4C1AZmBZBomyiCV/JjnjbMxkQovRRqCjXOvWGLzRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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