SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '638b85e06f580f1f2fbcfed144f2a12b75f23d6282e0193b97323917307c7b01' 
  AND token = '3dq7PXLKPbbl6gboYBlQjystCwVR/Jy0H/BIwt1nCVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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