SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c038a79f782a4242610cdcf597ffb495277712ad1dada15268a4808b8302c823' 
  AND token = 'KUM37T79LzY6BgTFwRqISAif//ztW3+ND5/KzdbkpQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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