SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac9a1d6ad476660321ebfc06be7fa49bf8c8d45c6a5de32cfb4cea997fe7098b' 
  AND token = 'kZtWzOw3KQTYSItc+fnbOqbYvreovV0pgpvuiAKPZj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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