SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '399519b88e481ebe9637fdbee7345d1fe19f9b7ebd0f073f70af4a3a6e62f01c' 
  AND token = 'QxPwH26L4+5ihN60+ZbiNwSNV5PUh+eE6ihn0+FyX90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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