SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5ba7396fa84365f2514c0149c3e65da683026b5061a9c3fe26d03d1c089d43c' 
  AND token = 'iSIEyd8R1jLZoKqjk5sJWBurt580d6WCNvGtUOqOJ3E=' 
  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"
    }
  }
}