SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9642fda6644ee5f32ba0006ea1e98d2de3345372dc3ed0a6c95b711126bd40aa' 
  AND token = '6fWoUaI4UkcvcpSC61DTNIaFfGTnaKtbymU4zyGemjU=' 
  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"
    }
  }
}