SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f88afabd260aad90adc80fe0cb5644e67b89d47f67e79bddb3f5323384f9b69' 
  AND token = '/bSlJNl6Gex7VmEmNG+vHxjg2BETwz/6KioFtthtm24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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