SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0dfe4c3ce0e7440f05d467bb21c40f876ea42c0edbf83005db5d1f09283fbaad' 
  AND token = 'sthnWQyDMk2PLrhSJab77sHRywyaHS5+d6UjrFmpWpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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