SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '348ec3f2f2e9df0a333dd0674815ee5455a5a5c05ef53859994f789731b1fb62' 
  AND token = 'T5lGLY2QkXXuO5mak2ebs61UzoVhSHObns1eiGzLnEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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