SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64ec818422569a3c4dde236b4e538754b3cd4baddadcb01fc1c947fde6ad43a4' 
  AND token = 'kKVGw/DZ5ekwxeR10vgDR9hjqJ5rE6dzjswvmRqwQLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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