SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2147700ef4fd492b4a7c7e5ca7dc42b8deec1f9b10d144fa97210d761c323de' 
  AND token = 'PRwdv1PiSFmnVFrZLrc64JEuHYkisuHVMY3PNQnZ1vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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