SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46fffa23969e750799e13f12695c82da81e2d6dc670208d753aca63a8fcca9a5' 
  AND token = 'fj+Ksx2Im7bXpBdXRzroo871VCeI0NP5lQ0jxLWqrsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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