SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56f1789d68b74eacc2764e9188421bd435247efae5c4ebdf93292561a07f1c59' 
  AND token = 'LNX/Nv69cgM3K7gTymciYdoUmLmaNMiuQR4jjbiWK/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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