SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13943ccceb47ff7c26c3d05841174e2eab7100f1c1d5db986d90ca29b1e94934' 
  AND token = 'ILCLOu2twa1DHPtv6kXLzLFyBJv7tTAzxjQpuDyKK8U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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