SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98b1f7c1e4a7e041b0bb72f24cdf3d2d973da46adf94a3c52d725c6c62056f13' 
  AND token = 'OmI1ydsrqeaFezc1g8VtV9fflQsl9otMpw5JS8VDqgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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