SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a4850725ed9237914a5d7fb519816391c24b83a03918a1a1f6859fb8febcbd9' 
  AND token = '5szym+U1CuWsbxBzLUpMXWTw/TZb9qoB6x66Dlk6C4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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