SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a77295355bd493e2e0a5824c7651d6a1453197a01c0211131ee7b028d0a09e8d' 
  AND token = 'LV+9XtLyOHozJB9yWyi8I7BQXxSrBcSFkvnN/AIu1wY=' 
  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"
    }
  }
}