SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6b29f56aa4281bf5f19d46ae44a09cf65ca89825433a63bf1ddb55994937124' 
  AND token = 'JJpERsSvZHtjY4RTQAM5vtRFA+yzXGRljIgfFAygDbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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