SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f3e9b8361ca373b48a5002f00f56ebcad629e3d56018ff6c24c27856c87902a' 
  AND token = 'A+TLd86jGjd28MOulmXjFHtNtGjlOu3aEGnhwfOAIQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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