SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b36bf4c632c13af396f7d47557273f8e9370dcbf04e5957be2765368d848ccc3' 
  AND token = 'ypCnM8xk6DOF3Se0kVqUK9Miu/Xt0KuCDDtFqqBbryY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}