SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c796ab71e9fa908fac8484ef522dac5a15f16473a0d445160c63a78f18229844' 
  AND token = 'uGnHp65unl7dMBgVV1aNkTD3ICcHPpfVmGIyAPeEyAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}