SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1502f7f37361e8d1c88ec38acc80eef297710f3ba0b2ce88c88142cfea37f029' 
  AND token = 'CTMKvKuVGnhEvvfJP54dMvaMrMC1bz6ejCehOZK0uTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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