SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc4290176ca32f0f2dc9609623c2ec1be04514aeb30338c7f8299650f3b63947' 
  AND token = 'TKVlkiJMb3scSWhpKsSAKoB9spwmV9DHhB9UIDuu5Gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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