SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5326464c4833dd73056b47aee8cbcb2a146f476353b6a2ebd8138f9ee3d6c421' 
  AND token = '/UYNy8hiM3vHlOTjfz+DGoDKBiNaefVMzxmpPmtBw/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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