SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a7b726ea70a75ed2d25c3e599c6d7be2e765470047fb8e308f3b74397d13f19' 
  AND token = 'Agt8jh8zFPmx6DLvwLNPPqr4YcJ+gd+sH/i1xGFFfJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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