SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdb58a254a50f65c2b81f03eeca0829c659885ee5ff0873ab17583e7e90633e6' 
  AND token = 'n7Nx6y9XYCTw38k7eRhQW3M1rL+TlC3uHZN9QVq0bDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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