SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '252abb448ac96313a791de7bf77a7cee5c360322134fe5eebd6350c71550cdda' 
  AND token = 'RUx8rSJuhldf/tWZbLpz2e9h2rvcNvW4cbQLbhZFfE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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