SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '296de8415139dd2bd8918467a0df95c1e3940592585e6be526c9d29101f664d6' 
  AND token = 'PPr1gySgwgoyGtTnTfb/9OVOFAvbpFiAJuoU31gK4ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}