SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4fa2442eaa203018bc7eaf9784e59341c2278cbab2654aab603901e92a72b94' 
  AND token = 'M4bizPO6Pqueq7EIvHXGWRhR1yVxHEwH9PjwECgT7RM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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