SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d5971c210b19f91dd3060b2070e51cd61bfffa2217d219f368986925193db78' 
  AND token = 'IR7Y/F9Xk4TG5wN7gPjlj7+yR1DjGpHytoHAy10Uzjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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