SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd99ba56206f26f002ccfe4e5df0c02d259a8f05d04fae681da2af4f5e14c3a7f' 
  AND token = '56bXYQIgwTk4IcISfZnSR4asUkhOMgbFhlildUfk6zQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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