SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '64c99bd857ce8bc1adc526c9ed25f7036d32f3608da501223fdf4981a9332955' 
  AND token = 'Juemj9jzOdzvz0NBTXuJ7MfSlPkAN+tzUwLgNJGmEvk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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